GIFT  OF 


HAND-BOOK 


MINERAL   ANALYSIS 


BY 

PRIEDRICH  WOHLER, 

PROFESSOR  OF  CHEMISTRY  IN  THE  UNIVERSITY  OF  GOTTINQEN. 


EDITED  BY 

HENRY  B.  NASON, 

PROFESSOR  OF  CHEMISTRY  IN  THE  RENSSELAER  POLYTECHNIC  INSTITUTE, 
TROY,  NEW  YORK. 


PHILADELPHIA: 
HENRY     CAREY     BAIRD, 

INDUSTRIAL  PUBLISHER, 

406  Walnut  Street. 

mi. 


Entered  according  to  Act  of  Congress,  in  the  year  1870,  by 

HENRY  CAREY  BAIRD, 
in  the  Office  of  the  Librarian  of  Congress.     All  rights  reserved. 


;  /  i*  : 

* 


PHILADELPHIA: 
COLLINS,  PRINTER,  705  JAYNE  STREET. 


PREFACE  TO  THE  AMERICAN  EDITION. 


The  present  edition  of  WOHLER'S  HAND-BOOK  OF 
MINEKAL  ANALYSIS  is  a  translation  of  the  last  German 
with  some  changes  and  additions. 

A  few  of  the  methods  here  described  might  have 
been  omitted,  and  newer,  in  some  cases  preferable  ones, 
given  instead,  but  it  has  been  thought  advisable  to 
present  the  book  in  nearly  the  same  form  as  the  ori- 
ginal. 

Free  use  has  been  made  of  the  excellent  translation 
of  the  first  edition  by  Dr.  A.  W.  Hoffman,  and  frequent 
reference  had  to  the  French  edition  by  Messrs.  Gran- 
deau  and  Troost,  from  which  many  of  the  illustrations 
of  apparatus  have  been  taken. 

The  work  is  not  intended  to  take  the  place  of  larger 
and  more  complete  works  on  analysis,  but  it  is  believed 
that  it  will  be  found  a  convenient  companion  to  these 
in  the  laboratory. 

H.  B.  N. 
TROY,  N.  Y.,  Dec.  15,1870. 


339665 


PREFACE. 


THIS  collection  of  examples  for  illustrating  the  most 
important  processes  for  determining  the  composition 
of  mineral  substances,  is  designed  chiefly  for  use  in 
the  laboratory. 

It  is  drawn  up  under  the  impression  that  it  is  easier 
for  most  minds  to  obtain  a  clear  insight  into  general 
relations  and  laws  by  the  study  of  special  cases,  than, 
inversely,  to  acquire  a  knowledge  of  individual  cases 
by  first  directing  the  attention  to  general  rules.  An 
endeavor  has  been  made  to  arrange  the  book  in  such 
a  manner  as  still  to  leave  enough  to  demand  the  re- 
flection of  the  student  and  the  explanations  of  the 
teacher ;  the  latter  also  must  point  out  the  authority  for 
the  individual  methods  here  given,  and  also  which  he 
considers  the  best. 

FRIEDKIOH  WOHLER. 


CONTENTS. 


PAGE 

Preface  to  the  American  edition        ' .       ' .        .     r   .        .        3 
Preface        .         .         .         .         .         .      .'.'    *  .        .        .        4 

Chloride  of  sodium       .         .        .         .        .  »        .13 

Chloride  of  silver       ' .        .         .         ./.•'.'.'.      14 

Sulphate  of  soda 15 

Tartrate  of  potassa  and  soda >   .      16 

Sulphate  of  soda  and  ammonia  .  .  ' .  .  .  .  18 
Sulphate  of  potassa  and  magnesia  .  .  .  .19 

Carbonate  of  potassa  and  magnesia  .  .  ,  .  .21 
Epsom  salt  and  Glauber's  salt  .  .  .  .  .  "  .  21 
Phosphate  of  soda  and  .ammonia  .  '.  .  '.  '.  .  22 
Phosphate  of  magnesia  and  ammonia  .  .  *  .  23 
Chlorides  of  potassium,  sodium,  and  magnesium  .  . .  25 

Dolomite  and  bitter-spar    .. 27 

Bone-ash 27 

Apatite „     •  .        .29 

Barite,  celestite,  and  gypsum      ......      31 

Alumina-alum      .......        .        .       33 

Iron-ammonia-alum      ........       34 

Alumina-chrome-alum          .        .         .  .        .34 

"Wavellite  and  phosphates  of  alumina  in  general  .  .  36 
Spinel.  (Alumina  and  magnesia  in  general)  ...  37 

Alumina  and  sesquioxide  of  iron 38 

Phosphoric  acid  and  sesquioxide  of  iron  ....  41 
Hematite  and  liraonite  V  '.  .  .  »  •  •  42 
Magnetite  .  '.  '.  .  \  \  ".  ^  *  .  44 
Siderite  '.  ;  ".  .  .  ',«  •  .  .  •  •  46 
Bog  iron-ore  .  '*  .  '.-  .  .  .  .  '\*  .  49 
Wet  assay  of  iron  "•  .  "»  *•  •  .  •  •  50 


yi  CONTENTS. 

PAQB 

Iron  assay 52 

Sulphate  of  copper, 53 

Chalcopyrite •         .53 

Sphalerite,  or  blende 55 

Smithsonite 57 

Brass 58 

Oxides  of  manganese,  iron,  and  zinc   .        .        .        .        .59 

Cadmium  and  zinc       .         . 60 

Cadmium  and  copper  ........  60 

Galenite       .        .        .'*•".' 61 

White  lead         V     '.       ".        .        .       '.*       .        .        .62 

Pyromorphite      .        .         .        .         .        .         .         .         .  63^ 

Silver  and  lead    .        .        .        .         .         .         .         .         •  ~  65 

Silver  and  copper        ........  66 

Silver  assay         ....      "  .^       .        .      ..        .  67 

Gold  and  copper         ^        .         .      '._",'.      '  .        .        .  68 

Gold  and  silver .'       f        .        .  69 

Amalgams  ..........  70 

Mixtures  of  protoxide  of  mercury,  minium,  and  cinnabar    .  72 

Tin  and  copper    .                                  72 

Tin  and  lead 73 

Bismuth,  lead,  afid  tin 74 

Bismuth  and  copper 76 

Schweinfurt  green 76 

Arsenic  and  lead 77 

Arsenic  and  tin .         .78 

Tartar-emetic 80 

Antimony  and  lead 80 

Bournonite »        .  82 

Zinkenite >.        ..      ...  83 

Berthierite •    .         ...       .        .  84 

Ked  silver-ore •,       ?        .84 

Tin  and  antimony        ....         .        ;"   "•        •  87 

Arsenic  and  antimony         ...       V       V      '..      .  88 

Arsenic,  antimony,  and  tin  .        .        .       "./.*.".  90 

Tetrahedrite                                                                            .  91 


CONTENTS.  Vii 

PAOE 

German  silver  (argentan)     .        .        »..     '  .        .        .         .  97 

Niccolite    ••      -.    '-.        .      . .    .    ;.'      -»...*,   •     .  98 

Smaltite     , .      , .      ,.        I.       ;,        .  103 

Cobaltite    -.      -.      /.      -'•      •-..-        .        ...       ..        .104 

Manganese  and  cobalt,  or  nickel         .'..*"•.        .        .  107 

Meteoric  iron     ..      .. ',.       ...»       ?.  109 

Platinum  metals  and  ore     .       .*        .      "<•<: :' >.'      .,        .  Ill 

Iridosmine  and  platinum  residues      . .'      ..       ..       .'.        .  118 

Thallium '...      •; •'  \.~- "'  '..,. '•'...  '.  126 

Indium       .  .        .        .        7    . .      . .      . .  133 

Tellurium  ore ,  ^      ......  138 

Natrolite,  thomsonite,  &c.  .        .        .        •      *>•'     •**'.  ;    .  141 

Ilvaite         .        .         .        .        i        .        *;     -^    ;  .    ^  *  143 

Chrysolite  (olivine) -.  •,    •..•       .  144 

Datolite                                }      ..      •,.       ••«       -fc       -.        .  145 

Ulexite       ..      ..      ,. '••:.-.•      .        *       ••*.  ..-..*>,        .  146 

Orthoclase   .      .  .        ...      ....      .  .      . .      . .        .  147 

Pyroxene,  amphibole,  garnet,  idocrase,  epidote  .       -•„        .  150 

Beryl ,.      ,..     ^      ..       ,.        ,  151 

Topaz.      ..      ,.      ;.      .*      /*'     'v' : .-  -i,.,'  «*-.;•••  fv .;-..  153 
Fluorite       .      .  .      ,  .     %     .  .      .  .      .  .     ".  .     '  -.        i-154 

Cryolite 155 

Zircon .                 .        .  156 

Cerite *     ;  .      ;-.  158 

Gadolinite 1.      ..      ..      \      -.  164 

Thorite ...»      :*  .    >.      ->  167 

Triphylite    .        .        .        ...      ..•'=*'.,.•'*       -*  168 

Titanite  (sphene)        .     -<-t       ,v        .-:•:,       -..     •-...     •;  171 

Menaccanite.     (Titanic  iron.)     -.       -..'-%_            *.        .  172 

Eutile ...."..      1 .      . .        .175 

Columbite.     (Niobite.)      ,>      /.      ,;      ^l|      '-  .   •  176 

Tantalite      .         .         .       =.        ...      -;.  '     .      ;  .        .  177 

Wolframite          ...        .-<.        ....     -.. ;.'.   -.:•      .  178 

Scheelite      ....        .,--..,.,;•      .        .  181 

Wulfenite  (molybdate  of  lead)    .        r      \ '  '   -.  •  v.-'      .  181 
Molybdenite         .         .         .         .       "..'.;        .        .184 

Brown  iron-ore,  containing  vanadium  .        .       •»      ".        .  185 


yiii  CONTENTS. 

PAGE 

Vanadinite.     (Yanadate  of  lead) 187 

Chroraite.     (Chrome-iron-ore) 187 

Chromate  of  lead 

Uraninite 192 

Seleniferous  deposit  from  sulphuric  acid  chambers     .        .  195 

Selenium  soot 197 

Clausthalite.     (Selenide  of  lead)        .        .        .        .        .198 

Cast-iron 20° 

Ash  of  the  refining-hearth 205 

Glass 209 

Clay 210 

Common  limestone,  hydraulic  limestone,  marl     .        .  21JL 

Iodide,  bromide,  and  chloride  of  sodium     .        .        .        .  212 

Crude  common  salt 214 

Incrustations  from  salt-pans 215 

Mineral  waters,  well-waters,  saline  springs  .        .        .        .216 

Soils 224 

Ashes  of  plants 228 

Guano 232 

Oxalate  and  phosphate  of  lime 238 

Alkalimetry 240 

Valuation  of  manganese  ores 248 

Chlorimetry 250 

Analysis  of  nitre         .        .        .        .        .  .         .252 

Gunpowder          .        .        .         ...        .         .        .  254 

Hydrocyanic  acid .  255 

Ferrocyanide  of  potassium .        .        .                .        .        .  257 

Examination  for  arsenic  in  cases  of  poisoning    .        .        .  258 

Examination  for  phosphorus  in  cases  of  poisoning      .        .  278 

Silicates 285 

Separation  of  the  iron  and  manganese        ....  295 

Analysis  of  the  materials  soluble  in  nitrate  of  ammonia     .  296 

Examination  of  the  volatile  materials  in  silicates        .        .  300 

Equivalent  weights  of  the  elements     .....  304 

Equivalent  weights  of  compound  bodies     ....  306 

INDEX  309 


HANDBOOK 


OP 


MINERAL  ANALYSIS 


1.  CHLORIDE  OF  SODIUM. 

Nad. 

PERFECTLY  pure  crystallized  common  salt  is  strongly 
heated,  to  expel  adhering  moisture,  weighed,  dissolved 
in  water,  the  solution  slightly  acidified  with  nitric  acid, 
heated,  and  the  chlorine  precipitated  by  nitrate  of  sil- 
ver, the  liquid  being  at  the  same  time  violently  agitated 
by  stirring.  When  the  chloride  of  silver  has  com- 
pletely separated,  leaving  the  liquid  clear,  it  is  filtered 
off  and  washed  (with  as  little  exposure  to  light  as  pos- 
sible), first  with  hot  water  acidified  with  nitric  acid,  in 
order  that  it  may  not  pass  through  the  filter  and  sub- 
sequently with  pure  water.  When  the  precipitate  has 
been  perfectly  dried  it  is  removed  as  completely  as 
possible  from  the  filter,  and  fused,  in  a  weighed  porce- 
lain crucible,  over  the  gas-lamp.  The  filter  is  com- 
pletely incinerated  by  itself;  the  ashes  are  placed  upon 
the  cooled  chloride  of  silver,  and  heated,  first  with  a 
little  nitric  acid,  in  ordei"  to  oxidize  the  reduced  silver, 
2 


14  "  '  CHLCtHIpE  'O.F  .-SILVER. 

and  afterwards  with  a  few  drops  of  hydrochloric  acid ; 
the  excess  of  acid  having  been  expelled,  the  chloride 
of  silver  is  again  heated  to  fusion,  allowed  to  cool,  and 
weighed.  100  parts  of  AgCl  contain  24.73  chlorine 
(and  75.27  silver). 

The  liquid  in  which  the  chloride  of  silver  floats  can 
also  be  decanted  with  care  on  a  filter.  The  chloride 
can  be  collected  in  a  weighed  porcelain  crucible,  after 
washing,  dried,  gently  calcined,  and  weighed.  The 
chloride  of  silver  being  a  little  volatile,  there  is  danger 
of  loss  if  it  is  heated  to  fusion.  The  filter  is  burned  by 
itself  and  the  ashes  weighed  with  the. calcined  chloride. 

For  the  determination  of  the  sodium,  another  weighed 
portion  of  chloride  of  sodium  is  carefully  moistened, 
in  a  weighed  platinum  crucible,  with  concentrated  sul- 
phuric acid ;  after  some  time,  a  gentle  heat  is  applied 
until  all  the  chlorine  has  been  expelled  in  the  form  of 
hydrochloric  acid,  when  the  excess  of  sulphuric  acid  is 
carefully  evaporated,  and  the  residual  sulphate  of  soda 
finally  heated  to  redness,  a  fragment  of  carbonate  of 
ammonia  being  placed  in  the  crucible,  to  decompose 
any  acid  salt.  From  the  weight  of  the  sulphate  of 
soda,  that  of  the  sodium  is  calculated. 


2.  CHLORIDE  OF  SILVER. 

AgOI. 

In  order  to  determine  the  composition  of  chloride  of 
silver,  a  weighed  quantity  of  pure  silver  is  dissolved 
in  dilute  nitric  acid,  the  solution  precipitated  with 
dilute  hydrochloric  acid,  and  the  precipitated  chloride 
of  silver  treated  as  in  No.  1. 

Or  a  weighed  portion  of  fused  chloride  of  silver  may 
be  heated  with  a  low  flame;  in  a  bulb-tube,  through 


SULPHATE   OF  SODA. 
Fig.  1. 


15 


which  a  stream  of  hydrogen  is  passed  until  it  is  com- 
pletely reduced  to  metallic  silver,  which  is  then  weighed. 


3.  SULPHATE  OF  SODA. 
NaO;S03-flOHO. 

For  the  determination  of  the  water,  a  weighed  quan- 
tity of  the  salt  is  gradually  and  carefully  heated  in 
a  platinum  crucible,  until  the  whole  of  the  water  is 
expelled,  to  insure  which  the  heat  is  finally  raised  to 
ignition. 

The  sulphuric  acid  is  determined  by  dissolving  the 
salt  in  water  and  precipitating  with  chloride  of  barium. 
The  liquid  is  then  warmed,  and  must  not  be  filtered 
until  the  sulphate  of  baryta  has  completely  separated. 
The  clear  liquid  is  then  poured  upon  the  filter,  without 
the  precipitate,  which  is  stirred  up  with  hot  water, 
again  allowed  to  subside,  the  clear  liquid  being  poured 
upon  the  filter,  and  the  precipitate  once  more  treated 
in  the  same  way  before  it  is  thrown  upon  the  filter,  in 
order  that  none  may  pass  through  the  pores  of  the 


16  ROCHELLE  SALT. 

paper.  When  perfectly  washed,  it  is  dried,  separated 
as  much  as  possible  from  the  filter,  the  latter  being 
completely  incinerated,  and  its  ashes  added  to  the  pre- 
cipitate, which  is  then  ignited  and  weighed.  100  parts 
of  sulphate  of  baryta  contain  34.29  of  sulphuric  acid, 
or  13.71  of  sulphur.  The  amount  of  soda  is  deter- 
mined by  difference. 


4.  TARTRATE  OF  POTASSA  AND  SODA.* 
Seignette-salt ;  Eochelle-salt,  (K0;  NaO,  T  +  8  HO). 

The  estimation  of  the  water  requires  the  cautious 
application  of  heat  for  a  long  period.  The  salt  fuses 
even  below  100°,  and  enters  into  ebullition  at  120°, 
but  does  not  lose  the  whole  of  its  water  till  heated  to 
215°. 

To  determine  the  bases,  the  salt  is  ignited,  the  alka- 
lies dissolved  out  of  the  carbonaceous  mass  by  dilute 
hydrochloric  acid,  and  the  filtered  solution  evaporated 
to  dryness;  the  mixed  chlorides  are  heated  to  dull 
redness  in  a  covered  platinum  crucible  and  weighed. 
They  are  then  dissolved  in  a  little  water,  and  the  solu- 
tion mixed  with  a  moderately  concentrated  solution 
of  bichloride  of  platinum.  The  solution,  with  the  sus- 
pended precipitate,  is  evaporated  to  dryness  on  the 
water-bath,  the  dry  mass  digested  for  some  time  with 
alcohol,  and  the  potassio-chloride  of  platinum  col- 
lected upon  a  filter  which  has  been  dried  at  100°, 
and  weighed.  The  filtrate,  which  contains  the  sodio- 
chloride  of  platinum,  must  still  have  a  distinct  yellow 
color.  The  platinum-salt  is  washed  with  alcohol, 

*  Prepared  by  saturating  a  hot  mixture  of  water  and  powdered 
tartar  with  carbonate  of  soda,  filtering,  and  crystallizing. 


ROCHELLE-SALT.  17 

dried  at  100°,  and  weighed.     100  parts  correspond  to 
16.03  of  potassium,  or  19.33  of  potassa. 

The  amount  of  the  chloride  of  sodium  may  be 
ascertained  by  deducting  the  weight  of  the  chloride  of 
potassium  from  that  of  the  mixed  chlorides.  It  is 
safer,  however,  to  control  this  result  by  direct  deter- 
mination, for  which  purpose  the  filtered  liquid  is  care- 
fully evaporated  to  dryness,  and  the  mass  strongly 
ignited  in  a  covered  platinum  crucible;  in  order  to 
insure  the  complete  decomposition  of  the  chloride  of 
platinum,  the  ignition  should  be  repeated,  with  addi- 
tion of  a  few  crystals  of  oxalic  acid.  From  the  cooled 
mass,  the  chloride  of  sodium  is  extracted  with  water. 

When,  as  is  frequently  the  case,  the  two  alkalies 
are  present  as  sulphates,  together  with  an  excess  of 
acid,  the  greater  portion  of  the  latter  is  expelled  by 
careful  evaporation,  and  the  saline  mass  afterwards 
ignited  in  a  covered  platinum  crucible,  into  which 
small  fragments  of  carbonate  of  ammonia  are  from 
time  to  time  introduced.  The  joint  weight  of  the 
neutral  salts  thus  obtained  is  then  determined. 

In  order  to  convert  these  sulphates  into  chlorides, 
the  mass  is  moistened  with  water,  mixed  with  pure 
chloride  of  ammonium,  and  heated  in  a  covered  cru- 
cible until  the  excess  of  the  latter  salt  is  expelled ; 
this  operation  is  repeated  until  the  weight  is  constant, 
when  the  chlorides  are  separated  by  means  of  bichlo- 
ride of  platinum. 

Or  the  solution  of  the  sulphates  maybe  precipitated 
by  a  solution  of  pure  acetate  of  baryta,  the  precipitate 
filtered  off)  the  filtrate  evaporated  to  dryness,  and  the 
residue  ignited.  From  the  carbonized  mass,  water 
dissolves  the  alkalies  as  carbonates,  which  are  con- 
verted into  chlorides  by  treatment  with  hydrochloric 
acid. 

2* 


18  SULPHATE   OF   SODA-AMMONIA. 

5.  SULPHATE  OF  SODA  AND  AMMONIA.* 
NaO,  S03;  NH4O,  S03  +  4HO. 

To  determine  the  amount  of  soda,  a  weighed  portion 
of  the  salt  dried  at  50°  is  gradually  and  carefully 
heated  to  redness  in  a  platinum  crucible,  a  fragment 
of  carbonate  of  ammonia  being  held  in  the  latter,  at 
the  end  of  the  operation,  to  complete  the  removal  of 
the  excess  of  sulphuric  acid.  From  the  weight  of  sul- 
phate of  soda  obtained,  that  of  the  soda  is  calculated. 

The  sulphuric  acid  is  determined  in  another  weighed 
portion  of  the  salt,  which  is  dissolved  in  warm  water 
and  precipitated  by  chloride  of  barium.  From  the 
weight  of  the  sulphate  of  baryta,  after  filtering,  wash- 
ing and  igniting,  the  amount  of  sulphuric  acid  is  cal- 
culated. 

The  quantity  of  the  ammonia  may  be  estimated  ac- 
cording to  two  different  methods. 

a.  The  weighed  salt  is  dissolved  in  the  smallest  pos- 
sible quantity  of  water,  and  the  soluion  mixed  with 
excess  of  an  alcoholic  solution  of  bichloride  of  platinum, 
which  precipitates  the  ammonia  in  the  form  of  ammo- 
mo-chloride  of  platinum.  When  the  precipitate  is 
completely  separated,  it  is  filtered  off',  washed  with 
alcohol,  dried,  and  carefully  ignited  (see  No.  1).  From 
the  weight  of  the  residual  platinum,  that  of  the  ammo- 
nia is  calculated.  100  parts  of  platinum  correspond 
to  26.37  of  ammonia.  In  order  to  ascertain  that  the 
platinum  does  not  contain  any  sulphate  of  soda  or 
chloride  of  sodium  which  may  have  been  precipitated 
by  the  alcohol,  it  is  washed  with  water  and  again 
weighed. 

*  To  prepare  this  salt,  .two  equal  portions  of  dilute  sulphuric 
acid  are  taken,  the  one  neutralized  with  carbonate  of  soda,  then 
mixed  with  the  other,  ammonia  added  to  neutralization,  and  the 
solution  evaporated  to  the  crystallizing  point. 


SULPHATE   OF   POTASSA  AND   MAGNESIA.  19 

5.  By  distilling  the  weighed  salt  with  a  moderately 
concentrated  solution  of  soda,  the  ammonia  is  evolved, 
and  may  be  combined  with  hydrochloric  acid.  This 
is  best  effected  in  a  small  flask  furnished  with  a  fun- 
nel-tube by  which  the  solution  of  soda  is  introduced, 
and  a  long  condensing-tube,  the  end  of  which  dips 
into  moderately-strong  hydrochloric  acid.  The  liquid 
is  retained  in  ebullition  until  one-half  has  distilled 
over.  The  hydrochloric  solution  is  carefully  evapo- 
rated to  dryness  in  a  weighed  dish,  over  a  water-bath, 
and  the -residue  of  chloride  of  ammonium  weighed  ;  or 
it  may  be  converted  into  ammonio-chloride  of  plati- 
num, which  is  then  treated  as  above. 

After  determining  the  soda,  the  ammonia,  and  the 
sulphuric  acid,  the  quantity  of  the  water  may  be  ascer- 
tained by  difference.  It  may  also  be  controlled  by 
mixing  a  weighed  portion  of  the  powdered  salt,  in  a 
platinum  crucible,  with  an  excess  of  freshly-burnt 
lime,  free  from  water  and  carbonic  acid  ;  the  mixture 
is  covered  with  a  layer  of  lime,  the  whole  weighed, 
and  very  strongly  ignited  over  a  gas  burner.  The 
loss  of  weight  represents  the  joint  amount  of  the  am- 
monia and  water. 


6.  SULPHATE  OF  POTASSA  AND  MAGNESIA.* 
KO,  S03;  MgO,  S03H-6HO. 

This  salt  loses  all  its  water  at  133°.  The  sulphuric 
acid  is  determined  by  precipitation  by  chloride  of 
barium  (see  No.  3). 

For  the  estimation  of  the  magnesia,  another  weighed 
quantity  of  the  salt  is  dissolved  in  water,  mixed  with 

*  This  salt  'is  easily  obtained  in  crystals,  by  mixing  a  boiling 
saturated  solution  of  1  part  of  sulphate  of  potassa,  with  a  saturated 
solution  of  1^  part  of  sulphate  of  magnesia. 


20          SULPHATE   OF   POTASSA   AND    MAGNESIA. 

chloride  of  ammonium,  subsequently  with  ammonia, 
and  the  magnesia  precipitated  as  phosphate  of  mag- 
nesia-ammonia by  adding  phosphate  of  soda.  The 
precipitation  is  not  complete  till  after  the  lapse  of  twelve 
hours,  when  the  precipitate  is  collected  on  a  filter  and 
washed  with  a  mixture  of  3  parts  of  water  and  1  part 
of  caustic  ammonia,  in  which  it  is  perfectly  insoluble. 
After  drying,  it  is  ignited,  being  thus  converted  into 
2  MgO,  P05  which  contains  36.44  per  cent,  of  mag- 
nesia. The  potassa  may  be  determined  by  difference. 
If  a  direct  estimation  be  required,  as  is  frequently  the 
case,  especially  in  the  analysis  of  minerals,  the  salt  is 
dissolved  in  water,  and  the  sulphuric  acid  and  mag- 
nesia precipitated  by  a  hot  saturated  solution  of  hy- 
drate of  baryta.  The  excess  of  baryta  is  removed 
from  the  filtered  liquid  by  adding  a  mixture  of  ammo- 
nia and  carbonate  of  ammonia,  the  filtrate  saturated 
with  hydrochloric  acid,  evaporated,  the  chloride  of 
potassium  feebly  ignited  and  weighed. 

If  both  potassa  and  soda  be  present,  they  are  sepa- 
rated as  in  No.  4. 

From  the  mixed  precipitate  of  magnesia  and  sulphate 
of  baryta,  the  former  is  dissolved  by  diluted  sulphuric 
acid,  and  afterwards  precipitated  and  determined  as 
above. 

Another  method  consists  in  mixing  the  solution  of 
the  double  sulphates  of  magnesia,  and  the  alkalies  with 
freshly  precipitated  carbonate  of  baryta,  and  passing 
washed  carbonic  acid  through  the  mixture  for  a  con- 
siderable time.  The  sulphate  of  baryta  which  is  then 
produced  is  filtered  off,  the  solution  evaporated  to  dry- 
ness,  and  the  mass  heated  nearly  to  redness.  A  mix- 
ture of  carbonate  of  baryta,  magnesia,  and  alkaline 
carbonate  is  thus  obtained,  from  which  the  latter  may 
be  extracted  with  water,  converted  into  chloride,  and 
weighed. 


EPSOM-SALT  AND   GLAUBER'S   SALT.  21 

7.  CAKBONATE  OF  POTASSA  AND  MAGNESIA.* 
KO,  C02;  2(MgO,  C02)  +  9  HO." 

When  ignited,  this  salt  loses  three-fourths  of  its  car- 
bonic acid,  and  the  whole  of  its  water,  leaving  a  mix- 
ture of  carbonate  of  potassa  and  magnesia,  which  may 
be  separated  by  water,  and  quantitatively  determined, 
the  potassa  for  this  purpose  being  converted  into  chlo- 
ride of  potassium.  The  magnesia  should  not  be  washed 
longer  than  is  necessary,  since  it  is  not  entirely  insolu- 
ble in  water.  (Magnesia  is  more  soluble  in  hot  water, 
and  on  this  account  cold  is  preferable.) 

The  total  quantity  of  carbonic  acid  contained  in  the 
salt  is  determined  by  expelling  it  in  an  apparatus 
arranged  for  the  quantitative  determination  of  carbonic 
acid.  The  amount  of  water  may  then  be  inferred  by 
difference. 

The  joint  weight  of  the  water  and  carbonic  acid  may 
be  determined  by  fusing  a  quantity  of  vitrified  borax 
in  a  platinum  crucible,  weighing  when  cool,  intro- 
ducing the  salt,  again  weighing,  and  fusing  over  the 
gas  flame  until  all  the  carbonic  acid  is  evolved,  and 
the  fused  borax  becomes  clear.  The  loss  of  weight 
expresses  the  joint  amount  of  water  and  carbonic  acid. 


8.  EPSOM-SALT  AND  GLAUBER'S-SALT. 
MgO,  S03+7  HO  and  NaO,  SO3  + 10  HO. 

One  hundred  parts  of  pure  sulphate  of  magnesia 
give,  by  the  method  described  in  No.  6,  45.12  parts  of 
phosphate  of  magnesia.  A  specimen  of  Epsom-salt 

*  Obtained  in  crystals  on  mixing  a  solution  of  chloride  of  magne- 
sium with  a  warm  saturated  solution  of  bicarbonate  of  potassa. 


22  PHOSPHATE   OF   SODA   AND   AMMONIA. 

adulterated  with  Glauber's  salt  will  give  a  proportion- 
ally smaller  quantity  of  the  phosphate.  Since  45.12 
parts  of  2  MgO,  PO5  correspond  to  100  parts  of  crys- 
tallized sulphate  of  magnesia,  a  specimen  of  the  latter 
which  yields,  for  example,  only  40  parts  of  2  MgO, 
PO5  would  contain  only  88.3  per  cent,  of  true  Epsom- 
salt,  and  11.7  per  cent,  of  Glauber's-salt. 

In  order  to  test  Epsom-salt  for  Glauber's-salt,  the 
specimen  is  mixed  with  powdered  charcoal,  dried,  and 
heated  in  a  crucible  to  bright  redness.  If  sulphate  of 
soda  be  present,  water  will  dissolve  out  of  the  cold 
mass  sulphide  of  sodium,  which,  when  treated  with 
hydrochloric  acid,  is  converted  into  chloride  of  sodium, 
with  evolution  of  sulphuretted  hydrogen. 

Or  the  solution  of  the  salt  to  be  tested  may  be  pre- 
cipitated by  hot  saturated  baryta-water,  filtered,  the 
excess  of  baryta  precipitated  from  the  solution  by  a 
mixture  of  ammonia  and  carbonate  of  ammonia,  and 
the  filtrate  evaporated,  when,  if  any  Glauber's-salt  have 
been  present,  carbonate  of  soda  will  be  left. 


9.  PHOSPHATE  OF  SODA  AND  AMMONIA* 
NaO,  NH40,  HO,  P05+8  HO. 

A  weighed  quantity  of  the  salt  is  gradually  and 
cautiously  heated  in  a  platinum  crucible,  the  heat  being 
finally  raised  to  ignition,  and  continued  till  the  salt  is 
in  a  state  of  tranquil  fusion.  The  ammonia  and  water 
are  thus  expelled,  their  joint  amount  being  indicated 
by  the  loss  of  weight.  The  fused  residue  is  NaO,  P05. 

*  Six  parts  of  crystallized  phosphate  of  soda  are  dissolved,  with 
the  aid  of  heat,  in  2  parts  of  water,  and  in  this  solution  2  parts  of 
chloride  of  ammonium  are  dissolved.  Tlie  filtered  liquid  deposits 
crystals  of  the  new  salt  which  are  purified  by  solution  in  hot  atu- 
mouiacal  water  and  recrystallization. 


PHOSPHATE   OF   MAGNESIA   AND  AMMONIA.         23 

The  determination  of  the  ammonia  is  effected  as  in 
No.  5,  with  another  portion  of  the  salt. 

In  order  to  determine  the  phosphoric  acicl,  the  salt 
is  dissolved  in  water  and  mixed  with  chloride  of  am- 
monium, ammonia  and  sulphate  of  magnesia,  the  pre- 
cipitatate  being  treated  as  in  No.  6.  The  ignited 
2MgO,  P05  contains  63.55  per  cent,  of  phosphoric  acid. 

For  the  direct  determination  of  the  soda,  a  weighed 
quantity  of  the  salt  is  dissolved  in  water,  and  the  phos- 
phoric acid  precipitated  by  acetate  of  lead.  From  the 
filtered  liquid,  the  excess  of  oxide  of  lead  is  removed 
by  a  mixture  of  ammonia  and  carbonate  of  ammonia, 
the  solution  heated  to  ebullition,  filtered,  evaporated 
to  dryness  and  the  residual  acetate  ignited,  with  access 
of  air,  until  the  carbonate  of  soda  is  colorless. 

Asa  control  for  the  determination  of  the  phosphoric 
acid,  the  phosphate  of  lead  may  be  decomposed  by 
heating  with  dilute  sulphuric  acid,  and  the  phosphoric 
acid  precipitated  from  the  filtrate  by  sulphate  of  mag- 
nesia, as  directed  above. 


10.  PHOSPHATE  OF  MAGNESIA  AND  AMMONIA* 
2  MgO,  NH40,  P05+ 12  HO. 

By  ignition  the  salt  is  converted  into  2  MgO,  P05. 

The  ammonia  is  determined  by  dissolving  the  salt 
in  the  smallest  possible  quantity  of  hydrochloric  acid, 
mixing  the  solution  with  bichloride  of  platinum  and 
alcohol,  and  treating  the  ammonio-chloride  of  platinum, 
as  in  No.  5. 

In  order  to  separate  and  determine  the  phosphoric 

*  Prepared  by  precipitating  a  solution  of  sulphate  of  magnesia 
to  which  much  chloride  of  ammonium  has  been  added,  by  phos- 
phate of  soda,  and  washing  the  precipitate  with  dilute  ammonia. 


24        PHOSPHATE   OF  MAGNESIA   AND  AMMONIA. 

acid  and  magnesia,  the  ignited  salt  is  fused  in  a  plati- 
num crucible,  over  a  spirit-lamp,  with  4  parts  of  car- 
bonate of  potassa  and  soda.*  The  mass  is  digested 
with  water,  the  residual  magnesia  washed,  ignited  and 
weighed. 

The  alkaline  solution  is  neutralized  with  acetic  acid, 
and  the  phosphoric  acid  precipitated  by  acetate  of  lead. 
The  precipitate  is  filtered  off,  washed,  dried,  detached 
as  far  as  possible  from  the  filter,  which  is  incinerated 
in  a  porcelain  crucible,  in  which  the  precipitate  is 
then  gently  ignited  and  weighed.  Since  its  composi- 
tion is  variable,  the  quantity  of  the  phosphoric  acid 
cannot  be  calculated  from  it.  In  order  to  determine 
this  acid,  the  precipitate  is  dissolved  in  warm  dilute 
nitric  acid,  and  the  oxide  of  lead  separated  by  sulphuric 
acid,  alcohol  being  afterwards  added  to  complete  the 
precipitation. 

The  sulphate  of  lead  is  filtered  off,  washed,  ignited 
and  weighed.  From  the  amount  of  this  precipitate, 
that  of  the  phosphoric  acid  may  be  calculated. 

The  phosphate  of  magnesia  and  ammonia  may  also 
be  dissolved  in  acetic  acid,  the  phosphoric  acid  pre- 
cipitated by  acetate  of  lead,  the  excess  of  oxide  of  lead 
removed  from  the  filtrate  by  adding  a  mixture  of 
ammonia  and  carbonate  of  ammonia,  heating  and  filter- 
ing. The  solution,  which  contains  acetate  of  magnesia, 
is  evaporated,  and  the  residue  ignited,  until  the  mag- 
nesia is  perfectly  white. 

Another  method  of  separating  phosphoric  acid  and 
magnesia  consists  in  dissolving  the  ignited  salt  in  a 
little  hydrochloric  acid,  boiling  the  solution  for  some 
time  in  order  to  convert  the  phosphoric  acid  into  the 
tribasic  form,  and  mixing  it,  first,  with  solution  of 

*  Consisting  of  equivalent  proportions  of  KO,  C02  and  NaO,  CO2, 
or  13  parts  of  the  former,  and  10  of  the  latter.  Also  easily  obtained 
by  igniting  Seignette-salt  free  from  lime,  dissolving,  and  evapo- 
rating to  dryness. 


CHLORIDES   OF   POTASSIUM,  SODIUM,  ETC.  25 

sesquichloride  of  iron,  and  afterwards,  with  excess  of 
acetate  of  ammonia  ;  if  the  solution  be  now  boiled  for 
some  time,  all  the  phosphoric  acid  and  iron  are  pre- 
cipitated, and  the  magnesia  remains  in  solution.  The 
filtered  liquid  is  evaporated,  to  dryness,  the  residue 
heated  till  all  ammoniacal  salt  is  expelled  and  moistened 
with  sulphuric  acid  to  convert  the  magnesia  into  sul- 
phate. The  excess  of  acid  is  expelled  by  heat,  and  the 
residual  salt  gently  ignited ;  from  the  weight  of  this 
residue. that  of  the  magnesia,  and  consquently  of  the 
phosphoric  acid,  is  calculated. 


11.  THE  CHLORIDES  OF  POTASSIUM,  SODIUM,  AND 
MAGNESIUM. 

In  the  analysis  of  minerals  which  are  decomposed  by 
hydrochloric  acid,  there  is  .frequently  obtained,  after 
the  separation  of  the  other  constituents,  a  mixture  of 
the  above-mentioned  chlorides.  The  solution,  if  con- 
taining, as  is  generally  the  case,  ammoniacal  salts,  ^is 
evaporated  to  dryness,  and  the  mass  gently  ignited  in 
a  platinum  crucible  until  the  latter  are  volatilized.  The 
magnesia  and  alkalies  are  then  separated  according  to 
one  of  the  following  methods  : — 

I.  The  mass  is  moistened  with  a  concentrated  solu- 
tion of  carbonate  of  ammonia,  dried  and  ignited,  during 
which  operation,  a  fragment  of  carbonate  of  ammonia 
is  held  within  the  partially  closed  crucible.     This  pro- 
cess is  repeated  until  a  constant  weight  is  obtained. 
A  mixture  of  magnesia  and  alkaline  chlorides  is  left, 
from  which  the  latter  may  be  extracted  by  water.    This 
method  is  more  difficult  of  execution  in  proportion  as 
more  alkaline  chlorides  are  present. 

II.  The  residue  containing  the  three  chlorides  is 
mixed  in  a  platinum  crucible,  with  some  water  and  a 

3 


26  CHLORIDES  OF   POTASSIUM,  SODIUM,  ETC. 

quantity  of  finely -powdered  oxide  of  mercury;  the 
mixture  is  digested  for  some  time,  dried,  and  ignited 
in  a  covered  crucible,  when  all  the  chloride  of  magne- 
sium is  decomposed  and  converted  into  magnesia. 

III.  The  chlorides  are  dissolved  in  a  little  water,  and 
the  solution  boiled  for  a  long  time  with  freshly  preci- 
pitated carbonate  of  silver,  when  all  the  chloride  of 
magnesium  is  decomposed.  The  precipitate  is  filtered 
off)  washed,  and  the  precipitated  carbonate  of  magnesia 
dissolved  out  with  dilute  hydrochloric  acid. 

IY.  The  solution  of  the  bases  is  mixed  with  some 
sal-ammoniac  and  ammonia  in  excess,  and  the  mag- 
nesia precipitated  by  phosphate  of  ammonia  (see  No.  6). 
From  the  filtrate  the  ammonia  is  expelled  by  evapo- 
ration, and  the  excess  of  phosphoric  acid  precipitated 
by  acetate  of  lead  as  a  compound  of  phosphate  and 
chloride  of  lead.  The  excess  of  oxide  of  lead  is  pre- 
cipitated by  a  mixture  of  ammonia  and  carbonate  of 
ammonia;  the  liquid  digested,  and  the  precipitate 
filtered  off.  The  alkalies  are  then  obtained  by  evapo- 
ration. 

Y.  The  chlorides  are  converted  into  nitrates  by 
heating  with  about  six  times  their  weight  of  nitric  acid. 
The  solution  is  evaporated,  the  salts  moistened  several 
times,  digested  with  crystals  of  oxalic  acid  whereby  all 
the  nitric  acid  is  decomposed. 

From  the  residual  mixture  of  magnesia  and  alkaline 
carbonates,  the  latter  are  extracted  with  water. 

VI.  The  magnesia  may  be  precipitated  by  sesqui- 
carbonate  of  ammonia  and  ammonia,  and  washed  with 
the  same.     If  potash  is  present  in  this  precipitate  it 
may  be  dissolved  out  with  water  after  ignition. 

VII.  Should  the  three  bases  be  in  form  of  sulphates, 
the  process  indicated  in  No.  4  must  be  adopted,  or  they 
are  weighed  after  ignition,  dissolved  in  a  little  water, 
the  solution  weighed,  about  one  half  poured  ofi^  and 
the  remainder  weighed.     From  one  portion  the  mag- 


BONE-ASH.  27 

nesia  is  precipitated  by  ammonia  and  phosphate  of 
soda,  and  from  the  other  potassa  by  bichloride  of  pla- 
tinum. 


12.  DOLOMITE  AND  BITTER-SPAR. 
CaO,  C02;  MgO,  C02. 

The  mineral  dried  at  100°  is  dissolved  in  dilute  nitric 
acid,  the  solution  afterwards  heated,  in  order  to  oxidize 
any  protoxide  of  iron,  neutralized  with  ammonia,  heated 
to  ebullition  till  it  no  longer  smells  of  ammonia,  and 
rapidly  filtered  from  any  precipitate  of  sesquioxide  of 
iron.  The  lime  is  then  precipitated  by  oxalate  of  am- 
monia. When  the  precipitate  has  subsided, after  being 
digested  for  some  time,  it  is  filtered  off,  washed,  dried 
and  ignited ;  it  is  then  moistened  with  carbonate  of 
ammonia,  again  dried,  and  gently  heated.  It  is  weighed 
as  carbonate  of  lime.  Or  it  may  be  moistened  with 
concentrated  sulphuric  acid,  the  excess  of  acid  being 
expelled  by  evaporation  and  subsequent  ignition,  and 
weighed  as  sulphate  of  lime. 

After  the  filtered  liquid  has  been  mixed  with  excess 
of  ammonia,  the  magnesia  is  precipitated  by  phosphate 
of  soda,  and  the  precipitate  treated  as  in  No.  6. 

The  quantity  of  carbonic  acid  contained  in  the  min- 
eral may  be  determined  by  loss.  It  may  also  be  ascer- 
tained directly  by  means  of  the  apparatus  arranged  for 
the  quantitative  determination  of  carbonic  acid. 


13.  BONE-ASH. 
3CaO,PO5  with  3MgO,P05  and  CaO,C02. 

A  mass  of  white  burnt  bone  is  dissolved  in  dilute 
nitric  acid,  the  solution  digested  for  some  time  to  expel 


28  BONE-ASH. 

all  the  carbonic  acid,  and  the  phosphates  of  lime  and 
magnesia  precipitated  by  ammonia.  When  the  pre- 
cipitate has  separated,  the  solution,  which  contains  the 
lime  previously  in  combination  with  carbonic  acid,  is 
rapidly  filtered,  and  the  precipitate  thoroughly  washed 
with  ammoniacal  water. 

From  the  filtrate,  the  lime  is  precipitated  by  oxalate 
of  ammonia,  and  the  precipitate  treated  as  in  No.  12. 

The  precipitate  of  phosphates  of  lime  and  magnesia 
is  dissolved  in  the  smallest  possible  quantity  of  hydro- 
chloric acid,  and  the  lime  precipitated  by  neutral  oxa- 
late of  potassa.  The  mixture  is  digested  for  some 
time  at  a  gentle  heat,  to  promote  the  separation  of  the 
precipitate,  and  the  clear  supernatant  fluid  is  then  cau- 
tiously neutralized  with  carbonate  of  potassa,  in  order 
to  precipitate  the  oxalate  of  lime  dissolved  by  the 
liberated  oxalic  acid ;  as  soon  as  it  has  completely 
separated,  the  precipitate  is  filtered  off'.  From  the  fil- 
trate, which  contains  all  the  phosphoric  acid  and  mag- 
nesia, the  latter  is  precipitated  by  ammonia  as  phos- 
phate of  magnesia-ammonia,  which  is  treated  as  in 
No.  6. 

From  the  liquid  filtered  from  this  precipitate,  which 
must  contain  free  ammonia,  the  phosphoric  acid  is 
precipitated  by  sulphate  of  magnesia. 

The  very  small  quantity  of  fluoride  of  calcium  con- 
tained in  bones  can  only  be  detected  qualitatively  ; 
in  the  precipitate  obtained  by  saturating  the  solution  of 
bone-ash  in  nitric  acid  with  ammonia. 

Bone-ash  may  also  be  analyzed  in  the  following 
manner :  The  finely-powdered  substance  is  heated  for 
a  long  time,  nearly  to  boiling,  with  an  excess  of  dilute 
sulphuric  acid,  the  greater  part  of  the  water  is  then 
evaporated,  and  the  mass  mixed  with  twice  its  volume 
of  absolute  alcohol,  which  dissolves  the  phosphoric 
acid.  The  mixture  is  filtered,  and  the  sulphates  washed 
with  alcohol.  From  these  the  sulphate  of  magnesia 


APATITE.  29 

and  a  part  of  the  sulphate  of  lime  are  extracted  with 
water,  and  separated  as  in  No.  12.  The  sulphate  of 
lime  remaining  undissolved  is  ignited  and  weighed. 
The  phosphoric  acid  solution  is  mixed  with  water,  the 
alcohol  evaporated,  and  the  phosphoric  acid  then  pre- 
cipitated by  sulphate  of  magnesia  and  ammonia  as  in 
No.  6. 

A  third  method,  based  upon  the  insolubility  of 
phosphate  of  binoxide  of  tin  in  nitric  acid,  is  as  fol- 
lows :  The  weighed  bone-ash  is  heated  in  a  flask,  with 
moderately  strong  nitric  acid,  and  several  times  its 
weight  of  pure  tin  (tin-foil),  the  weight  of  which  must 
be  accurately  known ;  the  contents  of  the  flask  are 
heated  to  ebullition,  diluted  with  water,  and  the  binox- 
ide of  tin,  which  contains  the  whole  of  the  phosphoric 
acid,  is  filtered  off,  washed,  dried,  ignited  and  weighed. 
The  difference  between  the  weight  of  this  precipitate 
and  that  of  the  binoxide  of  tin  which  should  be  fur- 
nished, by  the  amount  of  metal  employed,  is  due  to 
phosphoric  acid.  The  separation  of  the  lime  and  mag- 
nesia contained  in  the  solution  is  effected  as  in  No.  12. 

A  fourth  method,  applicable  in  general  for  the  sepa- 
ration of  phosphoric  acid  from  bases,  consists  in  dis- 
solving the  substance  to  be  analyzed  in  a  small  quan- 
tity of  nitric  acid,  adding  nitrate  of  silver,  some  car- 
bonate of  silver,  and  shaking  the  mixture.  All  the 
phosphoric  acid  combines  with  the  oxide  of  silver  and 
is  precipitated,  while  the  bases  remain  in  solution  and 
may  be  separated  from  the  excess  of  silver  by  hydro- 
chloric acid.  • 


14.  APATITE. 
3  (3  CaO,  P05)  + CaCl  (or  +  CaF). 

For  the  determination  of  the  chlorine,  a  weighed  por- 
tion of  the  mineral  (which  need  not  be  powdered)  is 

5* 


30  APATITE. 

dissolved  in  dilute  nitric  acid,*  and  the  chlorine  pre- 
cipitated by  nitrate  of  silver. 

In  order  to  detect  the  small  quantity  of  fluorine 
which  is  contained  in  some  specimens  of  apatite,  the 
finely  powdered  mineral  is  mixed,  in  a  platinum  cru- 
cible, with  concentrated  sulphuric  acid,  and  the  crucible 
covered  with  a  glass  plate  coated  with  a  thin  film  of 
wax,  through  which  some  characters  have  been  written 
with  a  needle;  the  crucible  is  then  heated  with  a  flame 
so  small  as  not  to  melt  the  wax.  If  fluorine  be  pre- 
sent, the  characters  are  found  etched  upon  the  glass 
after  the  removal  of  the  wax.  The  quantity  of  the 
fluorine  is  inferred  from  the  loss  of  weight  in  the  whole 
analysis. 

The  phosphoric  acid  and  lime  may  be  determined 
by  the  methods  described  in  the  analysis  of  bone-ash. 
The  following  process  may  also  be  employed. 

The  mineral  is  dissolved  in  nitric  acid,  in  a  dish,  and 
so  much  pure  mercury  added  that,  after  saturating  the 
acid,  a  portion  still  remains  undissolved.  The  mixture 
is  then  evaporated  to  perfect  dryness  on  the  water-bath. 
Should  it  still  emit  an  odor  of  nitric  acid,  this  acid 
must  be  completely  expelled  by  adding  more  water, 
and  again  evaporating  to  dryness.  The  mass  is  treated 
with  water,  filtered  through  the  smallest  possible  filter, 
and  the  residue,  which  contains  all  the  phosphoric 
acid,  well  washed. 

The  solution  contains,  besides  the  excess  of  the  mer- 
cury-salt, the  whole  of  the  lime.  The  suboxide  of 
mercury  is  precipitated  by  hydrochloric  acid.  Any 
protoxide  of  mercury  which  may  have  been  formed,  is 
precipitated  from  the  filtrate  by  ammonia.  If  the  mine- 
ral contain  iron,  or  other  bases  precipitable  by  ammo- 

*  Many  compact  apatites,  when  treated  with  nitric  acid  leave 
a  small  quantity  of  crystalline  powder,  which  is  cryptolite  (phos- 
phate of  protoxide  of  cerium). 


HEAVY  SPAR,  CELESTJNE,  AND   GYPSUM.  31 

nia,  these  will  remain  behind  on  igniting  this  preci- 
pitate. From  the  solution,  which  should  be  filtered 
rapidly,  and  with  as  little  exposure  to  air  as  possible, 
the  lime  is  precipitated  by  oxalate  of  ammonia. 

The  filter  with  the  mercury-residue,  which  contains 
the  phosphoric  acid,  is  well  dried,  and  the  contents 
thrown  into  a  platinum  crucible  in  which  they  are 
mixed  with  carbonate  of  potassa  and  soda  ;  the  filter 
is  rolled  up  and  buried  in  a  mixture.  The  crucible 
is  now  heated  (but  not  to  redness)  under  a  chimney 
with  a  good  draught,  until  the  mercury  is  volatilized, 
after  which  the  mass  may  be  heated  to  redness  and 
fused.  It  is  then  dissolved  in  water,  an  excess  of  hy- 
drochloric acid  added,  and  the  phosphoric  acid  precipi- 
tated by  ammonia  and  sulphate  of  magnesia. 


15.  BARITE,  CELESTITE,  AND  GYPSUM, 
BaO,  S03.— SrO,  S03.— CaO,  S03  +  2  HO. 

The  water  in  gypsum  is  determined  by  ignition. 
The  salts  of  strontia  and  lime  are  converted  into  car- 
bonates by  action  of  a  solution  of  carbonate  of  ammo- 
nia at  ordinary  temperature,  while  the  sulphate  of 
baryta  remains  unaltered. 

At  a  boiling  heat  or  with  carbonate  of  soda  the 
decomposition  is  not  so  complete. 

The  mixed  salts  must  be  finely  powdered  and  well 
washed  with  cold  water.  Nitric  acid  dissolves  the 
strontia  and  the  lime,  but  does  not  act  upon  the  sulphate 
of  baryta. 

The  latter  can  be  decomposed  by  fusing  with  four 
times  its  weight  of  carbonate  of  potassa  and  soda. 

The  mass  is  then  treated  with  boiling  water,  the 
carbonate  of  baryta  filtered  off'  while  hot,  and  washed 
with  boiling  water. 


32  HEAVY-SPAR,  CELESTINE,  AND   GYPSUM. 

The  filtered  solution  is  carefully  neutralized  with 
hydrochloric  acid,  the  sulphuric  acid  precipitated  by 
chloride  of  barium,  and  the  precipitate  treated  as  in 
No.  3. 

The  earthy  carbonates  are  dissolved  in  dilute  nitric 
acid,  taking  care  to  obtain  a  nearly  neutral  solution, 
which  is  then  evaporated  to  perfect  dryness  in  a  flask 
capable  of  being  closed.  The  saline  mass  is  treated 
with  about  twice  its  volume  of  a  mixture  of  equal 
volumes  of  ether  and  absolute  alcohol,  with  which  it 
is  allowed  to  digest,  in  the  closed  flask,  for  a  long  time, 
being  frequently  shaken,  but  not  heated.  The  mix- 
ture dissolves  the  nitrate  of  lime  only.  The  mixture 
is  filtered,  and  the  undissolved  nitrate  of  strontia 
washed  with  absolute  alcohol  in  a  closely  covered 
funnel. 

The  alcoholic  solution  is  diluted  with  water,  the 
greater  part  of  the  alcohol  evaporated,  and  the  lime 
precipitated,  as  in  No.  12,  by  oxalate  of  ammonia. 

The  nitrate  of  strontia  is  dried  at  100°  and  weighed, 
or  may  be  converted  into  a  sulphate  with  sulphuric 
acid. 

To  separate  carbonates  of  baryta  and  strontia  they 
are  dissolved  in  nitric  acid,  the  solution  concentrated 
and  the  baryta  precipitated  by  freshly -prepared  hy- 
drofluo-silicic  acid,  previously  mixed  with  an  equal 
volume  of  alcohol.  The  silico-fluoride  of  barium  is 
collected  on  a  weighed  filter,  washed  with  weak  spirit, 
and  dried. 

The  filtrate  containing  the  strontia  is  mixed  with 
sulphuric  acid,  evaporated  to  dryness,  the  sulphate  of 
strontia  ignited,  and  weighed. 

If  baryta  and  lime  only  are  to  be  separated,  the 
solution  is  largely  diluted,  the  baryta  precipitated  by 
sulphuric  acid,  and  the  lime  separated  from  the  filtrate 
by  oxalate  of  ammonia,  after  previously  neutralizing 
with  ammonia. 


ALUMINA-ALUM.  S3 

For  the  separation  of  baryta  and  strontia,  neutral 
chromate  of  potassa  rnaj  also  be  employed,  which  pre- 
cipitates all  the  baryta  as  chromate;  the  latter  is  washed, 
dried,  ignited  and  weighed.  It  is  necessary,  however, 
that  the  solution  should  be  perfectly  neutralized  and 
largely  diluted.  The  strontia  may  afterwards  be  pre- 
cipitated by  neutral  carbonate  of  ammonia. 

The  neutral  salts  of  lime,  mixed  with  a  solution  of 
arsenious  acid,  give  with  ammonia  a  precipitate  of 
arsenite  of  lime.  The  salts  of  strontia  and  baryta 
treated  in  the  same  way  do  not  form  a  precipitate.  On. 
the  other  hand,  the  presence  of  strontia  in  a  salt  of  lirne 
may  be  shown  by  a  clear  solution  of  sulphate  of  lime. 


16.  ALUMINA-ALUM. 
KO,  S03;  A1203,  3  S03  +  24  HO. 

A  weighed  quantity  of  the  pure  salt  is  dissolved  in 
water,  and  the  sulphuric  acid  precipitated  by  chloride 
of  barium  (see  No.  3). 

From  the  solution  filtered  from  the  sulphate  of  ba- 
ryta, the  alumina  is  precipitated,  together  with  the 
excess  of  baryta  which  has  been  added,  by  a  mixture 
of  carbonate  of  ammonia  and  free  ammonia.  After 
gently  heating  for  some  time,  the  precipitate  is  filtered 
off,. the  solution  evaporated,  and  the  saline  mass  heated 
till  all  the  chloride  of  ammonium  is  volatilized.  The 
gently-ignited  residue  is  chloride  of  potassium. 

The  precipitate  containing  alumina  and  baryta  is  dis- 
solved in  dilute  hydrochloric  acid,  and  the  baryta  pre- 
cipitated by  sulphuric  acid. 

From  the  solution  filtered  from  the  sulphate  of 
baryta,  the  alumina  is  precipitated  by  carbonate  of 
ammonia,  or  better,  by  sulphide  of  ammonium,  either 
of  which  effects  a  more  complete  precipitation  than 
caustic  ammonia. 


3-t  ALUMINA-CHROME-ALUM. 

The  precipitated  hydrate  of  alumina  is  well  washed, 
for  which  purpose  hot  water  is  to  be  preferred,  and 
strongly  ignited  in  order  to  expel  the  water. 

The  water  contained  in  the  alum  is  determined  by 
loss.  It  may  also  be  estimated  directly  by  carefully 
exposing  the  salt  for  a  very  long  time  to  a  gradually 
increasing  heat,  which  must  finally  be  raised  to  dull 
redness. 


17.   IRON- AMMONIA- ALUM.* 
NH40,  S03;  Fe203,  3  S03  +  24  HO. 

At  a  strong  red  heat,  this  salt  is  entirely  decom- 
posed, leaving  pure  sesquioxide  of  iron. 

The  determination  of  ammonia  is  effected  as  in  No. 
5  ;  that  of  sulphuric  acid  according  to  No.  3. 

In  order  to  control  the  determination  of  the  sesqui- 
oxide of  iron,  another  portion  of  the  salt  is  dissolved 
in  water,  and  the  sesquioxide  precipitated  by  ammonia. 
The  precipitated  hydrate  is  washed,  dried,  and  ignited. 


18.  ALUMINA-CHEOME-ALUM.t 
KO,S03; 


The  sulphuric  acid  is  precipitated  by  chloride  of 
barium  as  in  No.  3. 

*  Powdered  red  or  brown  iron-stone  is  digested  with  concen- 
trated sulphuric  acid  ;  the  white  sulphate  thus  produced  is  dis- 
solved in  water,  the  solution  mixed  with  sulphate  of  ammonia, 
filtered  and  allowed  to  crystallize. 

f  Three  parts  of  finely-powdered  bichromate  of  potassa  are  mixed 
with  15  parts  of  water,  and  1  part  of  concentrated  sulphuric  acid 
is  gradually  added,  so  that  no  evolution  of  heat  may  ensue;  sul- 
phurous acid  gas  is  then  passed  through  the  solution,  which  is 


ALUMINA  CHROME-ALUM. 


35 


The  alumina,  sesquioxide  of  chromium,  and  excess  of 
baryta  are,  precipitated  from  the  filtrate  by  carbonate 
of  ammonia  mixed  with  caustic  ammonia.  After  long 
standing,  the  precipitate  is  filtered  oft'  and  thoroughly 
washed. 

The  filtrate  is  evaporated,  the  residue  heated  to 
expel  chloride  of  ammonium,  and  the  residual  chloride 
of  potassium  gently  ignited  in  a  covered  crucible. 

The  mixed  precipitate  is  taken  and  washed  off  while 
wet  from  the  filter,  dissolved  in  dilute  sulphuric  acid, 
and  the  sulphate  of  baryta,  filtered  and  washed. 

An  excess  of  caustic  potassa  is  added  to  the  solution, 
which  is  then  saturated  with  chlorine  gas,  and  the 

Fig.  2. 


oxide  of  chromium  forms  a  yellow  solution  of  chro- 
mate  of  potassa. 

kept  cool,  so  that  its  temperature  may  not  rise  above  4(P,  until  the 
odor  of  the  gas  begins  to  be  perceptible.  After  some  time,  octohe- 
dra  of  pure  chrome-alum  are  formed,  which  may  be  set  aside.  The 
mother-liquor  is  mixed  with  an  equal  volume  of  a  solution  of  com- 
mon alum,  saturated  at  40°,  when  the  salt  in  question  separate! 
in  yellowish  octohedra. 


36      WAVELL1TE   AND  PHOSPHATES   OF   ALUMINA. 

Only  a  small  quantity  of  alumina  is  dissolved  which 
may  be  precipitated  by  gentle  digestion  witl^  carbonate 
of  ammonia. 

The  solution  of  alkaline  chromate  filtered  from  the 
alumina  is  carefully  mixed  with  excess  of  hydrochloric 
acid  and  some  alcohol,  and  heated  until  it  has  a  pure 
emerald-green  color.  The  sesquioxide  of  chromium 
is  precipitated  from  the  hot  solution  by  caustic  ammo- 
nia, washed,  dried,  ignited,  and  weighed. 


19.  WAVELLITE  AND  PHOSPHATES  OF  ALUMINA 
IN  GENERAL. 

A1203,P05  +  12HO. 

I.  The  mineral,  which  is  only  slightly  soluble  in 
hydrochloric  acid,  is  finely  pulverized  and  fused  with 
caustic  potassa  in  a  silver  crucible,  and  then  dissolved 
in  hydrochloric  acid,  and  tartaric  acid  added  to  the 
solution  until  it  gives  no  precipitate  with  excess  of 
ammonia.      Chloride  of  ammonium  and  sulphate  of 
magnesia  are  then  added,  and  the  solution  well  closed 
allowed  to  stand  for  24  hours,  and  the  precipitated 
phosphate  of  magnesia-ammonia  treated  as  in  No.  6. 
It  contains  basic  tartrate  of  magnesia,  which  after  igni- 
tion is  re-dissolved  in  hydrochloric  acid,  heated  for  a 
long  time,  and  again  precipitated  by  ammonia. 

II.  The  freshly-precipitated  alumina  is  dissolved  in 
the  smallest  possible  quantity  of  caustic  soda,  the  solu- 
tion diluted,  heated  to  ebullition,  and  a  solution  of 
silicate  of  soda  added  as  long  as  any  precipitate  of 
silicate  of  alumina  is  produced.     Lastly,  in  order  to 
precipitate  the  whole  of  the  silicic  acid,  a  concen- 
trated solution  of  sal  ammoniac  is  added,  the  solution 
again  boiled  and  filtered.    From  the  filtrate,  the  phos- 


SPINEL.  37 

phoric  acid  is  precipitated  by  ammonia  and  sulphate  of 
magnesia. 

The  silicate  of  alumina  is  decomposed  by  concen- 
trated hydrochloric  acid,  the  mass  evaporated  to  dry- 
ness  on  the  water-bath,  the  residue  moistened  with 
hydrochloric  acid,  the  alumina-salt  extracted  with  water, 
and  the  alumina  precipitated  by  carbonate  of  ammonia. 

III.  The  weighed  alumina  containing  phosphoric 
acid  is  dissolved  in  concentrated  nitric  acid,  and  the 
solution  heated  with  about  the  same  quantity  (accu- 
rately weighed)  of  pure  tin  (tin-foil).  The  mixture  is 
diluted  with  water,  heated  until  boiling,  and  the  bin- 
oxide  of  tin  which  has  combined  with  the  whole  of  the 
phosphoric  acid  is  filtered  off,  washed,  and  ignited. 
The  difference  between  the  weight  of  this  precipitate 
and  that  of  the  binoxide  of  tin  which  should  have  been 
furnished  by  the  metal  employed  represents  the  phos- 
phoric acid.  The  alumina  is  then  precipitated  from 
the  solution  by  sulphide  of  ammonium. 

Or  chloride  of  tin  is  added  to  the  solution  of  phos- 
phate of  alumina,  heated  to  boiling,  and  the  oxide  of 
tin  and  all  the  phosphoric  acid  precipitated  by  sul- 
phate of  soda.  If  sesquioxide  of  iron  is  present,  a 
portion  of  it  is  thrown  down.  The  accuracy  of  this 
method  is  not  yet  determined. 


20.  SPINEL.     (ALUMINA  AND  MAGNESIA  IN 
GENERAL.) 

MgO,Al203. 

The  mineral  is  very  finely  pulverized  in  a  steel 
mortar  separated  from  the  iron  with  hydrochloric  acid, 
and  then  fused  with  at  least  six  times  its  weight  of 
4 


38  ALUMINA   AND  SESQUIOXIDE   OF  IRON. 

bisulphate  of  potassa.*  It  should  be  kept  in  a  state 
of  fusion  for  a  long  time,  without  the  disengagement 
of  too  much  sulphuric  acid.  The  mass  is  then  dis- 
solved in  water  containing  a  little  hydrochloric  acid, 
chloride  of  ammonium  added,  and  the  alumina  pre- 
cipitated by  ammonia.  In  order  to  free  it  from  any 
magnesia,  the  fluid  is  heated  to  boiling  until  no  more 
ammonia  is  given  oft'.f  The  gelatinous  alumina  is  fil- 
tered, and  allowed  to  partially  dry  upon  the  funnel 
when  it  may  be  completely  washed.  It  is  ignited  and 
weighed.  The  magnesia  is  precipitated  by  phosphate 
of  soda  and  ammonia.  Many  specimens  of  spinel  con- 
tain a  little  protoxide  of  iron  and  silica. 

The  red  spinel  contains  sesquioxide  of  chromium, 
which  may  be  separated  from  the  alumina  as  in  No.  18. 


21.  ALUMINA  AND  SESQUIOXIDE  OF  IRON. 

The  mixture  of  the  two  is  dissolved  in  hydrochloric 
acid,  the  greater  part  of  the  excess  of  acid  evaporated, 
the  splution  mixed  with  an  excess  of  pure  solution  of 
potassa  and  heated  nearly  to  the  boiling  point.  The 
alumina  is  thus  dissolved,  the  sesquioxide  of  iron  being 
left  behind  of  a  dark  brown  color.  The  solution  is 
filtered  off,  acidulated  with  hydrochloric  acid,  and  the 
alumina  precipitated  by  sulphide  of  ammonium. 

The  sesquioxide  of  iron,  which  contains  some  potassa, 
is  dissolved  in  hydrochloric  acid,  re-precipitated  by 
ammonia,  and  ignited. 

This  method  of  separation  is  unsafe,  and  unless  re- 
peated more  than  once,  incomplete.  It  is  better  to  heat 

*  Prepared  by  heating  equal  parts  of  neutral  sulphate  and  con- 
centrated sulphuric  acid  to  a  dull  red  heat  until  the  the  mixture 
flows  quietly. 

f  The  same  process  as  in  the  separation  of  alumina  and  lime. 


ALUMINA   AND   SESQUIOXIDE   OF   IRON.  39 

the  acid  solution  to  ebullition,  to  add  sulphite  of  soda, 
in  order  to  reduce  the  sesquioxide  of  iron  to  the  state 
of  proto-sesquioxide,  replace  the  solution  over  the 
lamp,  boil  for  some  time  and  then  neutralize  with  car- 
bonate of  soda,  and  afterwards  boil  with  excess  of 
caustic  soda  until  the  precipitate  is  black  and  pul- 
verulent. 

The  tendency  to  bumping  preceding  the  actual  ebul- 
lition of  the  fluid,  may  be  guarded  against  by  means 
of  a  spiral  coil  of  platinum  wire  placed  in  the  liquid, 
or  by  constant  agitation  of  the  latter ;  when  ebullition 
has  opce  set  in,  there  is  no  further  need  of  these  pre- 
cautions. Remove  the  liquid  now  from  the  gas,  allow 
to  deposit,  pass  the  clear  fluid  through  a  filter,  which 
must  not  be  over-porous,  boil  the  precipitate  again  with 
a  fresh  quantity  of  solution  of  soda,  then  wash  it  by 
decantation  and. afterwards  on  the  filter  with  hot  water. 
Acidify  the  alkaline  filtrate  with  hydrochloric  acid, 
boil  with  some  chlorate  of  potassa  (to  destroy  any  traces 
of  organic  matter),  concentrate  by  evaporation,  and 
precipitate  the  alumina  by  sulphide  of  ammonium  or 
ammonia.  The  boiling  of  the  precipitated  oxides  with 
the  solution  of  soda  is  best  effected  in  a  large  silver 
or  platinum  dish.  The  soda  must  be  free  from  alumina 
and  silica.  Or  the  very  dilute  solution  of  both  bases 
may  be  neutralized  with  carbonate  of  soda,  mixed 
with  sulphite  of  soda  and  heated  until  no  sulphurous 
acid  is  given  off.  All  the  alumina  is  precipitated, 
while  the  iron  remains  in  solution.  The  precipitate  is 
ignited.  The  solution  of  iron  is  concentrated,  mixed 
with  some  chlorate  of  potassa  and  hydrochloric  acid 
and  heated.  After  the  sulphur  has  been  filtered  off 
the  iron  is  precipitated  by  ammonia. 

The  separation  may  be  obtained  by  placing  the 
mixed  precipitate,  ignited  in  a  porcelain  boat,  which  is 
placed  in  a  tube  of  the  same  material  heated  to  red- 
ness, through  which  a  current  of  dry  hydrogen  is 


40 


ALUMINA   AND   SESQUIOXIDE   OF   IRON. 


passed,  and  which  it  is  necessary  to  maintain  until  it 
is  completely  cool.  Then  there  should  be  substituted 
in  place  of  the  current  of  hydrogen,  a  current  of  hy- 
drochloric acid  gas,  which  transforms  the  iron  into 
volatile  chloride  and  leaves  the  alumina,  which  is 
weighed.  A  complete  description  of  this  process  of 
separation  of  iron  and  alumina  may  be  found  in  the 
article  on  silicates.  The  apparatus  is  arranged  as  fol- 
lows: L  is  a  gas  furnace  upon  which  is  placed  a  salt 
bath  I.  In  the  bottle  H  there  is  placed  some  fresh 
chloride  of  sodium,  on  which  is  poured  concentrated 
hydrochloric  acid. 

Fig.  3. 


Then  the  bottle  H  is  placed  in  cold  water  and  sul- 
phuric acid  gradually  poured  upon  it,  taking  care  that 
the  mixture  does  not  become  heated,  and  stopping 
when  vapors  of  hydrochloric  acid  begin  to  form.  It 


PHOSPHOEIC   ACID   AND   SESQUIOXIDE   OF   IRON.      41 

is  sufficient  to- heat  this  mixture  to  50°  or  60°  to  evolve 
a  steady  current  of  hydrochloric  acid  gas. 

The  amount  of  sesquioxide  of  iron  may  be  inferred 
from  the  loss  of  weight,  and  the  result  controlled  by 
collecting  the  chloride  of  iron  which  passes  over  and 
weighing  it. 


22.  PHOSPHORIC  ACID  AND  SESQUIOXIDE  OF  IRON.* 

In  order  to  separate  phosphoric  acid  from  sesqui- 
oxide of  iron,  the  compound  is  ignited  with  at  least  an 
equal  weight  of  carbonate  of  potassa  and  soda  (No.  10), 
the  resulting  mass  exhausted  with  water,  the  solution 
supersaturated  with  hydrochloric  acid  and  then  with 
ammonia,  and  the  phosphoric  acid  precipitated  by  sul- 
phate of  magnesia. 

The  residual  sesquioxide  of  iron  retains  some  alkali. 

Or  the  sesquioxide  of  iron  containing  phosphoric 
acid  is  dissolved  in  hydrochloric  acid,  precipitated  by 
ammonia,  and  digested  with  excess  of  sulphide  of  am- 
monium (without  previous  filtration),  until  all  the 
sesquioxide  is  converted  into  sulphide  of  iron.  When 
the  liquid  is  no  longer  green,  but  of  a  pure  yellow 
color,  it  is  filtered  off,  and  the  phosphoric  acid  imme- 
diately precipitated  by  sulphate  of  magnesia. 

For  the  accurate  quantitative  separation  of  a  small 
quantity  of  phosphoric  acid  from  a  large  quantity  of 
sesquioxide  of  iron,  the  latter  is  dissolved  in  hydro- 
chloric acid,  and  the  solution  heated  to  ebullition  with 
sulphite  of  soda  till  its  color  has  changed  to  a  bright 
green,  when  all  the  sesquioxide  of  iron  is  converted 

*  For  analyses  for  practice,  the  phosphate  of  sesquioxide  of  iron 
is  prepared  by  precipitating  sesquichloride  of  iron  with  phosphate 
of  soda.  Or  a  mixture  of  phosphates  may  be  prepared  by  precipi- 
tating a  solution  containing  sesquichloride  of  iron,  chloride  of 
calcium,  chloride  of  magnesium,  and  chloride  of  manganese. 

4* 


42  HEMATITE.      L1MONITE. 

into  protoxide.  The  solution  is  boiled  till  it  no  longer 
smells  of  sulphurous  acid,  neutralized  with  carbonate 
of  soda,  and,  in  order  to  produce  a  little  sesquioxide 
of  iron,  mixed  with  a  very  little  chlorine- water,  the 
quantity  of  which  must  be  regulated  according  to  the 
amount  of  phosphoric  acid  which  is  present.  The 
solution  must  now  be  mixed  with  an  excess  of  acetate 
of  soda,  when  phosphate  of  sesquioxide  of  iron  sepa- 
rates as  a  white  precipitate.  Chlorine- water  is  then 
added,  drop  by  drop,  until  the  liquid  has  assumed  a 
reddish  color,  when  it  is  boiled,  so  that  the  precipitate 
may  collect,  and  be  filtered.  From  this  precipitate 
the  phosphoric  acid  is  separated  by  sulphide  of  ammo- 
nium, as  directed  above. 

Or  it  may  be  dissolved  in  hydrochloric  acid,  boiled 
with  sulphite  of  soda,  and  afterwards  with  excess  of 
caustic  soda,  till  the  precipitate  is  converted  into  black 
proto-sesquioxide  of  iron,  which  is  filtered  off.  The 
solution  is  acidified,  and  the  phosphoric  acid  precipi- 
tated as  above. 


23.  HEMATITE,  Fe203,  AND  LTMONITE,  Fe2O3,  3  HO. 

For  the  determination  of  the  water,  weighed  frag- 
ments of  the  ore  are  heated  to  redness,  for  a  long  time, 
in  a  platinum  crucible.  If  the  mineral  decrepitates, 
it  must  first  be  finely  powdered. 

In  order  to  determine  the  oxygen,  the  fragments  of 
ignited  limonite  or  of  hematite  are  heated  to  redness 
in  a  weighed  bulb-tube  of  very  infusible  glass  (the 
bulb  being  as  small  as  possible),  through  which  a 
stream  of  dry  hydrogen,  free  from  arsenic,  is  transmit- 
ted as  long  as  any  water  is  formed. 

In  order  to  purify  hydrogen  it  is  passed  through  the 
U  tubes  containing  pumice  or  fragments  of  porcelain 


HEMATITE.      LIMONITK. 


43 


dipped  in  a  solution  of  acetate  of  lead,  sulphate  of  sil- 
ver, and  caustic  potassa;  the  first  absorbs  the  sulphuric 

Fig.  4.  • 


acid,  the  second  absorbs  the  combinations  of  hydrogen 
with  phosphorus  and  arsenic,  and  the  last  thecarburet- 

Fig.  5. 


44:    '  MAGNETITE. 

ted  hydrogen.  The  reduction  must  be  effected  at  the 
highest  temperature  of  the  gas-lamp,  for  otherwise 
the  reduced  iron,  even  when  cool,  may  reoxidize  and 
sometimes  inflame  in  the  air.  It  is  safer  to  reduce  the 
oxide  in  a  small  porcelain  boat,  placed  in  a  tube  of 
porcelain,  which  is  heated  by  a  charcoal  fire,  or  over 
the  gas  furnace. 

The  reduced  iron  is  heated  in  a  stream  of  hydro- 
chloric acid  gas.  Silicic  acid,  which  is  often  contained 
in  limonite,  is  then  left  undissolved,  and  may  be 
weighed. 


24.  MAGNETITE.* 
FeO,  Fe2O3. 

To  determine  the  amount  of  oxygen  which  is  com- 
bined with  the  iron,  the  proto-sesquioxide  is  reduced 
by  hydrogen,  as  in  No.  23. 

"  If  the  substance  contain  only  proto-sesquioxide  of 
iron,  the  whole  of  the  iron  may  be  determined  by  dis- 
solving in  hydrochloric  acid,  heating  with  some  chlo- 
rate of  potassa,  to  convert  all  the  protochloride  into 
sesquichloride,  and  adding  ammonia  to  precipitate  the 
sesquioxide  of  iron,  which  is  washed,  dried,  ignited, 
and  weighed. 

If  other  constituents  be  present  the  total  amount  of 
iron  may  be  determined  as  follows:  The  substance  is 
dissolved  in  an  excess  of  hydrochloric  acid,  the  proto- 
chloride converted  into  sesquichloride  by  addition  of 
chlorate  of  potassa,  and  all  free  chlorine  expelled  by- 
boiling.  The  solution  is  then  diluted  with  water  until 
the  flask  is  more  than  half-full;  a  weighed  strip  of 
bright  sheet-copper  is  placed  in  the  solution,  the  flask 
closed  by  a  cork  furnished  with  a  narrow  glass  tube, 

*  Forge-scales  have  a  similar  composition. 


MAGNETITE.  45 

and  the  liquid  heated  to  ebullition.  It  is  'retained  at 
this  temperature  until  the  dark-brown  color  originally 
observed  has  changed  to  a  pale  yellowish-green.  The 
whole  of  the  iron  is  now  contained  in  the  solution  as 
protochloride,  in  consequence  of  the  formation  of  sub- 
chloride  of  copper.  The  orifice  of  the  little  tube  is 
closed  air-tight,  and  the  solution  allowed  to  cool  some- 
what. The  flask  is  then  filled  with  hot  water,  the  liquid 
poured  off' from  the  undissolved  copper,  which  is  to  be 
washed,  first  with  dilute  hydrochloric  acid,  then  re- 
peatedly with  water,  dried,  and  weighed.  The  atomic 
weight  of  copper  is  to  that  of  iron  as  the  quantity  of 
copper  dissolved  is  to  that  of  the  iron  sought. 

In  order  to  determine  directly  the  amount  of  pro- 
toxide and  sesquioxide  of  iron  present  in. a  substance, 
it  must  be  dissolved  in  hydrochloric  acid.  The  follow- 
ing is  the  method  adopted:  The  compound  is  dissolved 
in  an  excess  of  concentrated  hydrochloric  acid,  in  a 
flask  filled  with  carbonic  acid,  and  afterwards  closed; 
the  flask  is  then  nearly  filled  up  with  water,  previously 
boiled,  and  a  weighed  strip  of  copper  introduced;  the 
closed  flask  is  placed  in  water,  which  must  be  gradually 
heated  to  boiling,  the  subsequent  process  being  con- 
ducted and  the  result  calculated  as  directed  above. 

Or  the  weighed  substance  is  placed  in  a  flask  closed 
with  a  cork,  and  furnished  with  tubes  for  ingress  and 
egress,  and  with  a  funnel-tube  passing  to  the  bottom 
of  the  flask,  which  is  to  be  filled  with  carbonic  acid. 
Hydrochloric  acid  is  then  added  through  the  funnel- 
tube,  and  the  solution  assisted  by  heat,  whilst  carbonic 
acid  is  allowed  to  stream  through  the  apparatus.  The 
solution  is  afterwards  diluted,  through  the  funnel-tube, 
with  boiled  water,  and  a  milky  mixture  of  carbonate 
of  baryta  with  water  gradually  added;  this  precipitates 
the  whole  of  the  susquioxide  of  iron,  while  the  protox- 
ide remains  in  solution.  When  the  supernatant  liquid 
has  become  clear,  it  is  decanted  through  the  egress- 


46  SIDERITE. 

tube,  the  precipitate  again  mixed  with  water,  and  after 
the  clear  liquid  has  been  again  decanted,  quickly  thrown 
upon  a  filter,  and  rapidly  washed,  air  being  excluded, 
with  water  which  has  been  previously  boiled  and  al- 
lowed to  cool. 

The  iron  precipitate  is  dissolved  in  dilute  hydro- 
chloric acid,  the  baryta  separated  by  sulphuric  acid, 
and  the  sesquioxide  of  iron  precipitated  by  ammonia. 

The  solution,  which  contains  the  protoxide  of  iron, 
is  mixed  with  hydrochloric  acid  and  chlorate  of  potas- 
sa,  and  concentrated  by  evaporation;  the  baryta  is  then 
precipitated  by  sulphuric  acid,  and  afterwards  the  ses- 
quioxide of  iron  by  ammonia. 


25.  SIDERITE. 

FeO,  CO,,,  frequentlv  containing  MnO,  CO^— CaO,  CO2, 
"and  MgO,  CO2. 

I.  The  best  method  of  analysis,  which  is  especially 
applicable  where  but  little  manganese  is  present,  is  the 
following:  A  weighed  portion  of  the  powdered  ore, 
previously  dried,  is  dissolved  in  hydrochloric  acid, 
with  the  aid  of  heat,  nitrate  or  chlorate  of  potassa  be- 
ing added  from  time  to  time,  so  that  the  whole  of  the 
protoxide  of  iron  is  sure  to  be  converted  into  sesqui- 
chloride.  The  solution,  which  must  still  be  acid,  so 
that  chloride  of  ammonium  may  be  formed,  is  diluted, 
and  gradually  neutralized  with  dilute  ammonia,  until 
it  has  acquired  a  dark  brown-red  color,  and  a  small 
quantity  of  hydrated  sesquioxide  of  iron  is  precipi- 
tated. The  whole  of  the  sesquioxide  of  iron  is  then 
separated  by  neutral  succinate  of  ammonia,  while  prot- 
oxide of  manganese,  lime,  and  magnesia  remain  in 
solution.  The  precipitated  succinate  of  sesquioxide  of 
iron  is  rapidly  filtered  off,  washed  with  cold  water, 


SIDERITE.  47 

dried,  and  gradually  heated  to  redness  in  a  porcelain 
crucible,  with  free  access  of  air;  till  it  is  converted  into 
pure  sesquioxide  of  iron. 

The  filtrate  is  feebly  acidulated  with  hydrochloric 
acid,  evaporated  to  dryness,  and  heated  till  all  ammo- 
niacal  salts  are  expelled. 

The  residue  is  then  dissolved  in  a  small  quantity  of 
water,  with  addition  of  hydrochloric  acid,  the  solution 
saturated  with  chlorine,  and  the  manganese  precipitated 
as  hydrated  sesquioxide  by  addition  of  ammonia.  The 
liquid  is  rapidly  filtered  off,  so  that  no  carbonate  of 
lime  may  be  precipitated,  and  the  manganese-precipi- 
tate washed,  dried,  and  ignited,  when  it  is  converted 
into  brown  proto- sesquioxide. 

The  lime  and  magnesia  in  the  filtrate  are  separated 
as  in  No.  12. 

Or  the  manganese  may  be  precipitated  by  sulphide 
of  ammonium,  the  sulphide  of  manganese  rapidly  fil- 
tered off,  and  dissolved  in  hydrochloric  acid.  When 
all  the  sulphuretted  hydrogen  has  been  expelled  by 
evaporation,  the  solution  is  heated  with  carbonate  of 
soda,  when  the  manganese  is  precipitated  as  carbonate, 
which,  after  ignition,  leaves  the  brown  proto-sesqui- 
oxide. 

From  the  solution  filtered  from  the  sulphide  of  man- 
ganese, the  lime  and  magnesia  are  precipitated  as  in 
No.  12. 

II.  The  acid  solution  is  largely  diluted  with  water, 
and  carbonate  of  soda  gradually  added  (drop  by  drop, 
when  the  solution  is  neutral),  with  constant  stirring, 
until  all  the  sesquioxide  of  iron  is  precipitated.     The 
other  bases  remain  dissolved  in  the  free  carbonic  acid. 
The  manganese  is  then  best  precipitated  by  hypochlo- 
rite  of  soda,  in  the  cold. 

III.  When  a  larger  quantity  of  manganese  is  present, 
the  solution,  which  must  contain  the  iron  entirely  in 
the  form  of  sesquichloride,  and  must  not  be  too  acid, 


48  SIDERITE. 

is  gradually  mixed  with  carbonate  of  baryta,  which 
precipitates  the  sesquioxide  of  iron  only.  When  a 
slight  excess  of  carbonate  of  baryta  has  been  added, 
and  the  solution  well  stirred,  it  is  filtered.  The  washed 
precipitate  is  dissolved  in  dilute  hydrochloric  acid,  the 
baryta  precipitated  by  sulphuric  acid,  and  the  sesqui- 
oxide of  iron  by  ammonia. 

From  the  solution  which  contains  the  other  three 
bases,  the  dissolved  baryta  is  first  precipitated  by  sul- 
phuric acid,  and  the  solution  treated  as  in  No.  12. 

IV.  The  diluted  solution,  obtained  as  in  I,  is  neu- 
tralized with  carbonate  of  soda  till  it  has  a  dark  brown- 
red  color,  mixed  with  a  saturated  solution  of  acetate  of 
soda,  and  chlorine  gas  passed  into  it  which  precipitates 
the  manganese,  or  it  is  heated  to  ebullition,  when  the 
whole  of  the  sesquioxide  of  iron  is  precipitated. 

The  filtrate  is  neutralized  with  carbonate  of  soda, 
mixed  with  hypochlorite  of  soda  (containing  bicarbo- 
nate of  soda),  and  allowed  to  stand  in  a  closed  vessel 
for  twenty-four  hours,  when  the  manganese  is  precipi- 
tated as  hydrated  sesquioxide,  which  is  ignited  and 
weighed  as  proto-sesquioxide. 

From  the  filtered  liquid  the  lime  and  magnesia  are 
separated  as  above. 

V.  The  solution  of  oxide  of  iron  is  precipitated  by 
ammonia,  the  liquid  boiled  as  long  as  ammonia  is  given 
off,  and  the  oxide  of  iron  filtered  off,  which  is  now  free 
from  lime,  magnesia,  and  manganese.     It  may  be  fil- 
tered with  free  access  of  air,  for  the  fluid  contains  no 
free  ammonia.     The  solution  is  concentrated  by  evapo- 
ration and  the  three  bases  precipitated  by  an  excess  of 
carbonate  of  potassa,  and  boiled  until  ammonia  ceases 
to  be  disengaged. 

It  is  then  filtered,  the  precipitate  dissolved  in  nitric 
acid,  evaporated  to  dry  ness,  and  the  saline  mass  care- 
fully raised  to  a  dull  red  heat.  The  lime  and  mag- 


BOG   IRON   ORE.  49 

nesia  may  be  separated, by  very  dilute  nitric  acid  from 
the  oxide  of  manganese,  which  is  insoluble  in  the  acid. 


26.  BOG  IRON-ORE. 

Fe203,  3  HO,  with  MnO,  A1203,  CaO,  MgO,  Si03,  P05, 
As05. 

If  the  amount  of  iron  only  is  to  be  determined,  the 
process  with  copper  may  be  employed,  as  in  the  case 
of  magnetic  iron;  or  the  ore  may  be  subjected  to  the 
dry  assay.  The  complete  analysis  is  effected  in  the 
following  manner: — 

The  mineral,  dried  at  100°,  is  ignited,  and  the  water 
determined. 

Another  portion,  which  has  not  been  ignited,  is 
coarsely  powdered,  and  dissolved  in  hydrochloric  acid  ; 
the  solution  is  evaporated  to  perfect  dryness  on  the 
water-bath,  the  mass  dissolved  in  warm  dilute  hydro- 
chloric acid,  and  the  sand  and  silicic  acid  removed  by 
filtration.  The  latter  may,  after  ignition  and  weigh- 
ing, be  separated  from  the  sand  by  boiling  with  carbo- 
nate of  soda. 

The  hydrochloric  solution  is  boiled  with  an  alkaline 
sulphite,  until  it  no  longer  smells  of  sulphurous  acid,  to 
reduce  the  sesquichloride  of  iron  to  protochloride,  and 
the  arsenic  acid  to  arsenious  acid,  which  is  then  pre- 
cipitated by  sulphuretted  hydrogen,  as  tersulphide  of 
arsenic;  sometimes  mixed  with  a  little  sulphide  of 
copper. 

The  solution  is  boiled  till  the  sulphuretted  hydrogen 
is  completely  expelled,  precipitated  by  carbonate  of 
soda,  mixed  with  an  excess  of  caustic  soda,  and  boiled 
until  the  precipitate  becomes  pulverulent. 

The  solution  is  filtered  off.  It  contains  all  the  alu- 
5 


50  WET  ASSAY   OF  IKON. 

mina  and  part  of  the  phosphoric  acid,  which  are  sepa- 
rated as  in  No.  19. 

The  precipitate,  consisting  of  proto-sesquioxide  of 
iron,  carbonate  of  protoxide  of  manganese,  carbonate 
and  phosphate  of  lime  and  magnesia,  is  dissolved  in 
hot  nitric  acid;  the  solution  is  neutralized,  as  far 
as  possible,  with  carbonate  of  soda,  mixed  with  acetate 
of  soda,  and  boiled,  when  all  the  phosphoric  acid  and 
sesquioxide  of  iron  are  precipitated.  In  order  to  sepa- 
rate these,  the  precipitate  is  treated  as  in  No.  22. 

The  filtrate  contains  the  protoxide  of  manganese, 
lime,  and  magnesia,  which  are  separated  as  in  No.  25. 


27.  WET  ASSAY  OF  IRON. 
(Volumetric  Method.) 

The  process  for  determining  in  the  moist  way  with 
great  accuracy,  and  without  a  complete  analysis,  the 
amount  of  iron  contained  in  an  ore,  consists  in  ascer- 
taining the  number  of  measures  of  a  solution  of  per- 
manganate of  potassa  of  known  strength  which  may 
be  decolorized  by  the  solution  of  protoxide  of  iron 
obtained  from  a  given  quantity  of  the  ore.* 

One  equiv.=  1/980   grms.  of  crystallized   perman- 

r  *  To  prepare  the  permanganate  of  potassa,  10  parts  of  very  finely 
powdered  pyrolusite  are  mixed  with  7  parts  of  chlorate  of  potassa, 
the  mixture  saturated  with  a  very  concentrated  solution  of  10  parts 
of  hydrate  of  potassa  and  the  wet  mass  gradually  heated  in  an 
earthen  crucible  to  dull  redness,  so  that  it  cinders  together,  but 
does  not  fuse.  When  cool,  it  is  powdered,  treated,  in  a  flask,  with 
a  considerable  quantity  of  hot  water,  and  washed  carbonic  acid 
gas  passed  into  it  until  the  color  of  the  solution  has  changed  to  a 
purple-red,  and  the  excess  of  potassa  is  converted  into  the  carbo- 
nate. It  is  then  allowed  to  stand  until  the  solution  becomes  clear, 
which  is  poured  off  from  the  precipitate  and  evaporated  to  the 
point  of  crystallization.  The  salt  is  then  purified  by  recrystalli- 
zation. 


WET  ASSAY   OF  IRON". 


51 


ganate  of  potassa  converts  the  protoxide  of  iron  from 
10  equivs.  =  3'500  grms.  of  pure  iron  into  sesquioxide. 

So  that  if  19-80  grms.  of  the  salt  be  dissolved  in  1 
litre  (=1000  grms.  or  1000  cub.  cent.)  of  water  ;  100 
cub.  cent,  of  this  solution  will  correspond  to  3'50  grms. 
of  iron.  It  must  be  kept  in  a  well-stoppered  bottle. 

An  equivalent  quantity  (say  3*5  grms.,  or  half  that 
amount)  of  the  ore  to  be  tested  is  dissolved  in  concen- 
trated hydrochloric  acid,  in  a  capacious  flask,  by  the 
aid  of  heat.  If  the  insoluble  residue  of  foreign  mat- 
ters, such  as  clay,  silica,  &c.,  be  not  very  considerable, 
it  is  unnecessary  to  filter  the  solution.  The  iron  must 
now  be  entirely  reduced  to  the  state  of  protoxide,  either 
by  mixing  the  solution  with  several  times  its  volume 
of  a  saturated  solution  of  sulphurous  acid,  and  boiling 
so  long  as  any  trace  of  that  gas  is  perceptible ;  or,  bet- 
ter, by  allowing  a  piece  of  zinc,  free  from  iron,  to 
remain  in  the  liquid  until  its  color  is  changed  to  a  pale 
green.  It  is  then  decanted  from  the  zinc,  the  latter 
thoroughly  rinsed,  the  solution  diluted  with  the  washing- 


Fig.  6. 


Fig.  7.        Fig.  8.       Fig.  9.  Fig.  10. 


The  figures  6,  7,  8,  9,    10  represent  the  burette,  the  pipette,  and  the 
graduated  vessels  used  in  volumetric  analysis. 

water,  and  mixed  with  some  more  hydrochloric  acid  ; 
the  solution  of  permanganate  of  potassa  is  then  drop- 
ped in  from  a  burette  (see  Alkalimetry),  until  the 


52  IRON   ASSAY. 

yellow  color  which  the  solution  then  acquires  is  changed 
to  a  clear  red  by  adding  another  drop  of  the  perman- 
ganate. The  number  of  cubic  centimetres  of  the 
manganese-solution  which  have  been  employed,  at  once 
indicates  the  percentage  of  iron  in  the  ore. 

Instead  of  the"crystallized  permanganate  of  potassa, 
the  crude  solution  originally  obtained  in  the  prepa- 
ration of  that  salt  may  be  employed,  provided  it  be 
first  graduated — that  is,  quantitatively  tested  as  to  its 
oxidizing  power.  For  this  purpose,  3'5  grms.  (or  half 
that  quantity,  T75  grms.)  of  pure  iron-wire  are  dis- 
solved in  a  capacious  flask  by  concentrated  hydro- 
chloric acid,  with  the  aid  of  heat.  The  solution  is 
diluted  with  several  times  its  volume  of  cold  water, 
and  the  solution  of  permanganate  dropped  into  it,  as 
directed  above.  When  the  quantity  of  solution  em- 
ployed has  been  read  off,  the  whole  is  diluted  with  so 
much  water,  that  100  cub.  cents,  may  correspond  to  3'5 
grms.  of  iron.  It  must  be  kept  in  a  well-stoppered 
bottle. 


28.  IRON  ASSAY. 

The  weighed  iron-ore,  in  the  state  of  fine  powder, 
roasted  or  not,  as  the  case  may  be,  is  mixed  with  dried 
borax,  and  the  mixture  exposed  for  an  hour,  in  a  cov- 
ered crucible  lined  with  charcoal,  to  the  most  intense 
heat  of  a  wind-furnace  with  a  good  draught;  the  quan- 
tity of  borax  varies  according  to  the  nature  of  the 
iron-ore.  The  greater  the  quantity  of  extraneous  mat- 
ter which  is  present,  the  more  borax  it  requires.  For 
10  grms.  of  iron-ore,  3  grms.  of  borax  may  be  taken 
as  the  minimum,  10  grms.  as  the  maximum.  In  a  well 
conducted  assay,  all  the  iron  is  found  reduced  to  a  sin- 
gle well-fused  button.  If  the  iron  ore  contained  phos- 
phoric acid  the  crude  iron  will  contain  phosphorus. 


CHALCOPYRITE.  53 

29.  SULPHATE  OF  COPPER. 

(Blue  Vitriol.) 
CuO,S03 


For  analysis,  the  salt  is  purified  by  recrystallization. 

To  determine  the  water,  a  weighed  quantity  of  the 
dry  salt,  in  the  state  of  fine  powder,  is  heated  to  about 
200°,  until  it  has  become  perfectly  white,  and  has 
ceased  to  lose  weight. 

It  is  then  dissolved  in  water,  and  the  sulphuric  acid 
precipitated  by  chloride  of  barium,  as  directed  in  No.  3. 

For  the  determination  of  copper,  another  weighed 
portion  of  the  salt  is  dissolved  in  from  50  to  100  times 
its  weight  of  water,  in  a  dish  or  a  wide-mouthed  flask; 
the  solution  is  heated  until  boiling,  and  the  oxide  of 
copper  precipitated  by  caustic  potassa,  which  should 
not  be  added  in  too  large  excess.  The  brownish-black 
precipitate  is  filtered  off,  washed  with  hot  water,  dried, 
and  weighed. 

To  determine  the  amount  of  oxygen  in  the  oxide  of 
copper,  a  freshly-ignited  portion  is  introduced  into  a 
weighed  bulb-tube,  and  its  weight  carefully  ascertained  ; 
a  stream  of  dry  hydrogen,  free  from  arsenic,  is  then 
passed  through  the  tube,  the  bulb  of  which  is  heated 
to  redness  with  a  large  flame.  When  no  more  aqueous 
vapor  is  perceptible,  and  the  oxide  is  completely  re- 
duced to  the  metallic  state,  it  is  allowed  to  cool  in  the 
stream  of  gas,  and  weighed  as  soon  as  the  hydrogen  in 
the  tube  has  been  replaced  by  atmospheric  air. 


30.  CHALCOPYRITE. 
Cu2S,  Fe2S8. 

The  powdered  mineral  is  introduced  into  a  flask, 
placed  obliquely,  and  gradually  mixed  with  concen- 

5* 


54  CHALCOPYRITE. 

trated  nitric  acid  in  small  portions  at  a  time ;  the  con- 
tents of  the  flask  are  then  heated  until  either  the  whole 
is  dissolved,  or  the  metals  have  passed  into  solution 
together  with  a  portion  of  the  sulphur,  and  the  un- 
oxidized  sulphur  has  separated  in  the  form  of  a  yellow 
powder,  or  in  fused  drops  of  a  clear  yellow  color. 
The  solution  is  diluted  with  water,  and  decanted  from 
any  undissolved  sulphur,  which  is  well  washed,  dried 
in  a  porcelain  crucible,  at  a  gentle  heat,  and  weighed. 
It  is  then  burnt  in  order  to  ascertain  whether  it  contains 
any  metals  or  quartz,  &c.  Should  the  sulphur  "be 
separated  in  a  pulverulent  state,  it  must  be  collected 
on  a  weighed  filter,  washed,  and  dried  at  a  very  gentle 
heat. 

From  the  filtered  solution,  that  portion  of  the  sul- 
phur which  has  been  converted  into  sulphuric  acid  is 
precipitated  by  chloride  of  barium,  and  the  sulphate  of 
baryta  treated  as  in  No.  3.  Protracted  washing  with 
hot  water  is  necessary,  since  the  precipitate  has  carried 
down  some  nitrate  of  baryta. 

In  order  to  avoid  this,  the  mineral  may  be  dissolved 
in  concentrated  hydrochloric  acid,  with  gradual  addi- 
tion of  nitric  acid,  or  chlorate  of  potassa. 

The  excess  of  baryta  having  been  removed  from  the 
liquid  filtered  from  the  sulphate  of  baryta  by  means 
of  sulphuric  acid,  a  slow  stream  of  sulphuretted  hydro- 
gen is  passed  through  the  filtrate,  until  the  odor  of  the 
gas  is  distinctly  perceptible.  The  precipitated  sulphide 
of  copper  is  thrown,  as  rapidly  as  possible,  upon  a 
dried  and  weighed  filter,  and  well  washed  with  water 
containing  sulphuretted  hydrogen. 

It  is  then  dried  in  the  funnel  at  200°,  weighed,  a 
portion  of  it  introduced  into  a  weighed  bulb-tube, 
which  is  afterwards  again  weighed,  and  heated  in  a 
stream  of  hydrogen  until  it  no  longer  loses  any  sul- 
phur. It  is  thus  converted  into  Cu2S,  which  contains 
the  same  amount  of  copper  as  the  protoxide.  The 


SPHALERITE.  55 

weight  obtained  is  calculated  upon  the  whole  quantity 
of  sulphide  of  copper. 

Or  the  filter  with  its  contents  may  be  allowed  to  dry 
in  the  funnel,  the  precipitate  detached,  and  thrown 
into  a  beaker ;  the  filter  is  then  completely  incinerated, 
the  ash  added  to  the  sulphide  of  copper,  and  the  latter 
oxidized  with  agua-regia  till  the  sulphur  separates  of 
a  pure  yellow  color.  From  the  filtered  solution,  the 
protoxide  of  copper,  as  in  No.  29,  is  precipitated  at  a 
boiling  heat  by  caustic  potassa,  ignited  and  weighed. 

The  solution  filtered  from  the  sulphide  of  copper, 
containing  the  iron  in  the  form  of  protoxide,  is  heated 
nearly  to  boiling,  in  a  flask,  concentrated  if  necessary 
by  evaporation,  and  treated  at  the  same  time  with 
chlorate  of  potassa  in  small  portions,  until  all  the  prot- 
oxide of  iron  is  converted  into  sexquioxide,  which  is 
then  precipitated  by  ammonia,  washed,  dried,  and 
ignited. 

Notwithstanding  the  solubility  of  oxide  of  copper  in 
caustic  ammonia,  this  reagent  will  not  effect  its  com- 
plete separation  from  sesquioxide  of  iron,  since  the 
latter  carries  down  with  it  a  considerable  quantity  ~of 
oxide  of  copper  which  cannot  be  extracted  by  ammonia. 


31.  SPHALERITE,  OR  BLENDE. 

ZnS. 

The  solution  is  effected  just  as  in  the  case  of  chalco- 
pyrite.  -The  mineral  must  be  very  finely  powdered, 
and  very  concentrated  acid  must  be  employed. 

After  the  sulphuric  acid  which  is  produced  has  been 
precipitated  by  chloride  of  barium,  and  the  excess  of 
baryta  has  been  removed,  the  solution  is  saturated  with 
sulphuretted  hydrogen,  in  order  to  precipitate  any  cop- 
per and  cadmium  which  often  occur  in  small  quantities 


56  SPHALERITE. 

in  this  mineral.  The  precipitatate,  after  being  filtered 
off  and  washed,  is  treated  as  in  No.  36. 

The  first  filtrate,  which  contains  the  zinc  and  gene- 
rally a  little  iron,  is  heated  to  ebullition,  and  mixed, 
first  with  some  hypochlorite  of  soda  to  peroxidize  the 
iron,  then  with  excess  of  ammonia,  until  all  the  oxide 
of  zinc  is  redissolved,  and  the  sesquioxide  of  iron  pre- 
cipitated ;  the  latter  is  then  washed  and  ignited.  It 
cannot  be  obtained  by  this  method  perfectly  free  from 
oxide  of  zinc. 

From  the  filtrate,  the  zinc  is  precipitated  by  sulphide 
of  ammonium.  The  precipitate  should  not  be  filtered 
off  until  it  has  separated  from  the  liquid;  it  is  washed 
with  water  containing  a  little  sulphide  of  ammonium, 
and  digested  (together  with  the  filter),  while  yet  moist, 
with  concentrated  hydrochloric  acid,  the  solution  fil- 
tered off)  and  the  oxide  of  zinc  precipitated,  at  the 
boiling-point,  by  carbonate  of  soda.  The  precipitate  is 
washed,  dried,  ignited,  and  weighed  as  pure  oxide  of 
zinc. 

Or  it  may  be  dried  as  sulphide  of  zinc,  removed 
from  the  filter  as  much  as  possible,  which  is  burned, 
and  the  ashes  added  to  the  sulphide,  mixed  with  a  little 
sulphur,  placed  in  a  weighed  bulb  tube,  and  ignited  in 
a  current  of  hydrogen,  and  then  weighed  as  sulphide 
of  zinc. 

Sesquioxide  of  iron  may  be  more  completely  sepa- 
rated from  oxide  of  zinc  by  means  of  succinate  of  am- 
monia, as  described  in  No.  25,  or  by  carbonate  of 
baryta  (No.  25,  III.) 

If,  as  has  been  proposed,  the  solution  were  mixed 
with  acetate  of  soda,  so  as  to  convert  the  iron  and  zinc 
into  acetates,  and  treated  with  sulphuretted  hydrogen, 
not  only  zinc,  but  iron  also  would  be  precipitated. 


SMITIISOXITE.  57 

32.  SMITHSON1TE. 
ZnO,  C02. 

This  mineral  generally  contains  small  quantities  of 
protoxides  of  iron,  manganese,  lead,  and  cadmium, 
together  with  lime,  magnesia,  and  silicic  acid. 

It  is  dissolved  in  hydrochloric  acid,  the  solution 
evaporated  to  dry  ness,  the  mass  digested  with  concen- 
trated hydrochloric  acid,  diluted,  heated,  and  the  silicic 
acid  filtered  off. 

The  solution,  which  must  be  acid,  is  saturated  with 
sulphuretted  hydrogen,  which  precipitates  the  lead 
and  cadmium. 

This  precipitate  is  oxidized  with  concentrated  nitric 
acid,  a  little  sulphuric  acid  being  also  added,  evapo- 
rated to  dryness,  and  the  sulphate  of  cadmium  sepa- 
rated from  the  sulphate  of  lead  by  water.  (See  Lead 
and  Bismuth.) 

The  filtrate  is  boiled,  to  expel  the  sulphuretted  hy- 
drogen, and  treated  with  chlorate  of  potassa  to  perox- 
idize  the  iron.  From  the  solution,  which  must  still 
contain  free  chlorine,  the  sesquioxides  of  iron  and 
manganese  are  precipitated  by  excess  of  caustic  am- 
rnonia,  and  separated  as  in  No.  25. 

The  zinc  is  precipitated  from  the  filtered  solution, 
as  sulphide,  by  addition  of  sulphide  of  ammonium,  and 
the  precipitate  treated  as  in  No.  31.  The  solution  is 
rapidly  filtered  off)  with  as  little  exposure  to  air  as 
possible,  and  the  lime  precipitated  by  oxalate  of  am- 
rnonia  ;  the  magnesia  is  afterwards  separated  by  phos- 
phate of  soda. 

IF  a  specimen  of  this  mineral  consist  of  carbonate 
and  silicate  of  zinc,  their  relative  quantities  may  be 
approximately  determined  by  igniting  the  finely-pow- 
dered mineral,  and  digesting  it  with  a  mixture  of  car- 
bonate of  ammonia  and  free  ammonia,  which  dissolves 


58  BRASS. 

the  oxide  of  zinc  previously  in  combination  with  car- 
bonic acid,  leaving  the  silicate  untouched. 


33.  BRASS. 

The  alloy  is  dissolved  in  hydrochloric  acid  with 
gradual  addition  of  nitric  acid,  the  solution  diluted, 
and  the  copper  precipitated  by  sulphuretted  hydrogen. 
(See  No.  30.) 

The  excess  of  sulphuretted  hydrogen  is  expelled 
from  the  filtrate  by  boiling,  and  the  oxide  of  zinc  pre- 
cipitated from  the  hot  solution  by  carbonate  of  soda. 
(See  No.  31.) 

Oxide  of  zinc  cannot  be  entirely  separated  from 
oxide  of  copper  by  even  a  very  large  excess  of  caustic 
potassa. 

Too  little  zinc  is  usually  obtained  by  the  above  pro- 
cess, because  a  portion  is  carried  down  with  the  sul- 
phide of  copper.  The  separation  is  more  completely 
effected  by  neutralizing  the  diluted  solution  of  the 
alloy  with  ammonia,  and  digesting  with  a  slight  excess 
of  solid  hydrate  of  potassa  until  it  has  lost  its  color 
and  ammoniacal  odor.  The  oxide  of  copper  is  then 
filtered  off,  and  washed  with  hot  water.  From  the 
alkaline  solution,  the  zinc  is  precipitated  by  sulphide 
of  ammonium,  or  boiling  with  carbonate  of  soda. 

Another  accurate  method  is  the  following:  The  so- 
lution of  both  metals  is  saturated  with  sulphurous  acid 
and  the  copper  precipitated  as  white  subsulphocyanide 
by  sulphocyanide  of  potassium.  After  it  has  digested 
for  some  time,  the  subsulphocyanide  is  filtered,  a  little 
sulphur  added  and  ignited  in  hydrogen  gas,*  when  it 

*  The  precipitate  with  filter  ash  should  be  placed  in  a  porcelain 
crucible,  and  strongly  ignited  by  a  stream  of  hydrogen,  by  means 
of  the  gas  blowpipe. 


OXIDES   OF   MANGANESE,   IRON>   AND   ZINC.         59 

is  converted  into  Cu2S.  The  oxide  of  zinc  is  heated 
and  precipitated  with  carbonate  of  soda. 

This  method  may  be  used  also  for  the  separation  of 
iron  and  copper. 

The  brass  sometimes  contains  traces  of  tin.  It  is 
then  dissolved  in  hot  nitric  acid,  which  leaves  the  bin- 
oxide  of  tin  (containing  a  little  copper)  untouched. 

In  order  to  detect  a  small  quantity  of  lead  which 
frequently  occurs  in  brass,  the  sulphide  of  copper  pre- 
cipitated by  sulphuretted  hydrogen  is  oxidized  with 
fuming  nitric  acid,  the  mass  dried,  and  treated  with 
water,  which  leaves  thq  sulphate  of  lead  undissolved. 
Should  this  contain  sulphur,  it  must  be  burnt  off. 

Or  the  brass  may  be  dissolved  in  nitric  acid,  a  little 
sulphuric  acid  added,  the  solution  evaporated  to  dry- 
ness,  and  the  mass  treated  with  water. 

If  the  brass  be  placed  in  a  little  porcelain  boat,  and 
heated  to  redness  in  a  porcelain  tube  through  which  a 
rapid  stream  of  hydrogen  is  passed,  all  the  zinc  rnay 
be  volatilized. 


34.  OXIDES  OF  MANGANESE,  IRON,  AND  ZINC. 

The  solution,  which  must  contain  the  iron  in  the 
form  of  sesquioxide,  is  mixed  with  carbonate  of  soda 
until  a  permanent  precipitate  begins  to  appear;  it  is 
then  boiled  with  acetate  of  soda,  when  all  the  sesqui- 
oxide of  iron  is  precipitated. 

The  filtrate  is  mixed  with  acetic  acid,  and  the  zinc 
precipitated  by  sulphuretted  hydrogen. 

The  manganese  may  be  precipitated,  after  neutrali- 
zation, with  an  alkaline  hypochlorite,  or  by  boiling 
with  an  alkaline  carbonate. 


60  CADMIUM  AND   ZINC. 


35.  CADMIUM  AND  ZINC. 

The  alloy  of  the  two  metals  is  dissolved  in  hydro- 
chloric acid,  the  solution,  which  must  be  decidedly 
acid,  is  largely  diluted,  and  saturated  with  a  slow 
stream  of  sulphuretted  hydrogen,  which  precipitates 
all  the  cadmium  in  the  form  of  a  yellow  sulphide. 
The  latter  is  thrown  upon  a  weighed  filter,  and  dried 
at  100°  till  of  constant  weight. 

It  is  more  accurate  to  dissolve  the  sulphide  of  cad- 
mium in  hydrochloric  or  nitric  acid,  and  to  precipitate 
the  oxide  of  cadmium  from  the  solution,  as  white  car- 
bonate, by  means  of  carbonate  of  soda.  The  precipi- 
tate is  washed,  dried  and  ignited,  when  it  is  converted 
into  the  brown  oxide.  Previously  to  the  incineration 
of  the  filter,  the  precipitate  should  be  detached,  as  far 
as  possible. 

The  filtrate  is  boiled  to  expel  the  sulphuretted  hy- 
drogen, and  the  zinc  precipitated  from  the  hot  liquid 
by  carbonate  of  soda. 

Another  method  of  separation  consists  in  decom- 
posing the  solution  of  the  two  metals  by  considerable 
tartaric  acid,  and  then  adding  caustic  soda  to  distinctly 
alkaline  reaction,  dilute  with  considerable  water,  and 
boil  for  some  hours.  The  cadmium  is  alone  precipi- 
tated. The  zinc  may  be  precipitated  from  the  filtered 
solution  by  sulphide  of  ammonium. 


36.  CADMIUM  AND  COPPER. 

'Both  metals  may  be  precipitated  from  a  weak  acid 
solution  by  sulphuretted  hydrogen,  the  washed  pre- 
cipitate washed  off  from  the  filter,  boiled  with  dilute 
sulphuric  acid,  when  all  the  cadmium  will  be  dissolved. 

Or  the  washed  precipitate  of  both  metals,  with  the 


GALENITE.  61 

filter,  is  dissolved  in  hydrochloric  acid  with  a  little 
chlorate  of  potash,  the  solution  saturated  with  potassa, 
and  then  hydrocyanic  acid  added  until  the  precipitate 
is  again  dissolved.  From  this  solution  of  the  double 
cyanides  the  cadmium  may  be  precipitated  by  sulphu- 
retted hydrogen,  and  the  copper  will  remain.  The  sul- 
phide of  cadmium  is  treated  as  in  No.  35.  The  solu- 
tion of  copper  is  boiled  with  aqua  regia,  and  while  hot 
the  copper  precipitated  by  caustic  potassa. 

The  copper  maybe  separated  from  cadmium  as  from 
zinc,  by  sulphocyanide  of  potassium,  as  in  No.  33. 


37.  GALENITE. 
PbS. 

The  finely-powdered  mineral,  placed  in  a  capacious 
dish,  is  gradually  moistened  with  fuming  nitric  acid 
until  it  is  entirely  converted  into  white  sulphate  of 
lead ;  a  few  drops  of  sulphuric  acid  are  added,  to 
insure  complete  conversion,  the  mass  ignited  and 
weighed. 

If  the  residue,  previously  to  ignition,  be  treated 
with  water,  and  filtered,  only  traces  of  lead  are  found 
in  the  solution.  If  the  galena  contain  copper,  iron,  or 
silver,  they  will  be  detected  in  the  solution,  the  first 
two  by  ammonia,  and  the  silver  by  hydrochloric  acid. 

If  the  galena  be  oxidized  with  more  diluted  nitric 
acid,  the  residue  consists  of  a  mixture  of  sulphate  of 
lead  and  sulphur,  while  the  solution  contains  nitrate 
of  lead,  from  which  the  lead  may  be  precipitated  by 
sulphuric  acid,  or,  more  completely,  by  oxalate  of  am- 
monia, after  neutralization.  By  igniting  the  dried 
residue,  the  sulphur  is  volatilized,  and  sulphate  of  lead 
remains. 

When  boiled  with  a  solution  of  carbonate  of  soda, 
6 


62  WHITE    LEAD. 

the  sulphate  of  lead  is  converted  into  carbonate,  which, 
after  washing,  is  completely  dissolved  by  nitric  acid. 

Sulphate  of  lead  is  dissolved  to  a  great  extent  by  a 
mixture  of  tartrate  of  ammonia  and  free  ammonia. 
From  this  solution  it  may  be  completely  precipitated 
by  sulphide  of  ammonium  as  black  sulphide  of  lead, 
or  by  chromate  of  potassa,  in  the  form  of  yellow  chro- 
mate  of  lead. 

The  sulphate  of  lead  may  be  reduced  to  the  metallic 
state  by  fusion  with  four  times  its  weight  of  cyanide 
of  potassium. 


38.  WHITE  LEAD. 

2(PbQ,  OO2)-fPbO,HO 

frequently   mixed  with    BaO,  SO.,,— CaO,  SO3;— CaO, 
CQ2,  or  PbO,  S03. 

Pure  white  lead  is  perfectly  soluble  in  dilute  nitric 
acid.  The  oxide  of  lead  may  be  determined  by  igni- 
tion, after  drying  at  100°.  In  order  to  estimate  the 
water,  a  specimen,  whjch  has  been  dried  at  100°,  is 
ignited  in  a  tube  to  which  a  weighed  chloride-of-calcium 
tube  is  attached.  The  carbonic  acid,  which  is  expelled 
at  the  same  time,  is  determined  by  loss.  White  lead 
sometimes  contains  a  small  quantity  of  basic  acetate  of 
lead,  indicated  by  the  odor  of  acetone  which  is  per- 
ceived when  the  specimen  is  ignited. 

White  lead  adulterated  with  chalk  is  likewise  dis- 
solved, with  exception  of  traces  of  impurities,  by  nitric 
acid.  From  the  diluted  solution,  the  lead  is  precipi- 
tated by  sulphuretted  hydrogen,  the  sulphide  of  lead 
collected  upon  a  weighed  filter,  washed,  dried  at  100°, 
and  weighed.  From  the  solution,  after  neutralizing 
with  ammonia,  the  lime  is  precipitated  by  oxalate  of 
ammonia. 

If  barite  be  present  in  the  specimen,  it  is  left  be- 


PYROMORPHITE.  63 

hind  on  treatment  with  nitric  acid.  After  washing 
and  igniting,  it  is  weighed  and  analyzed  as  in  No.  15. 

Gypsum  would  also  be  in  great  measure  left  behind 
on  dissolving  in  nitric  acid.  It  may,  however,  be  en- 
tirely dissolved  and  separated  from  any  barite  pre- 
sent at  the  same  time,  by  boiling  with  a  large  quan- 
tity of  dilute  nitric  acid.  The  amount  of  gypsum 
present  may  be  inferred  from  that  of  the  sulphate  of 
baryta  obtained  by  precipitating  the  solution  with 
chloride  of  barium. 

Sulphate  of  lead  would  also  be  left  undissolved  by 
dilute  nitric  apid.  After  washing,  it  becomes  black 
when  treated  with  sulphide  of  ammonium  ;  it  is  soluble 
in  tartrate  of  ammonia  mixed  with  free  ammonia.  In 
a  mixture  of  sulphate  of  lead  and  sulphate  of  baryta, 
the  former  may  be  converted,  by  digestion  with  sul- 
phide of  ammonium,  into  sulphide  of  lead,  which  can 
be  transformed  into  chloride  by  treatment  with  con- 
centrated hydrochloric  acid,  and  may  then  be  dissolved 
out  by  water. 


39.  PYROMORPBITB. 
3(3PbO,P05)-r-PbCl* 

In  many  varieties,  the  chloride  of  lead  is  replaced 
by  chloride  of  calcium,  in  others,  a  part  of  the  phos- 
phoric acid  is  replaced  by  arsenic  acid.  The  green 
varieties  contain  traces  of  sesquioxide  of  iron  and  ses- 
quioxide  of  chromium  or  chromic  acid. 

Those  specimens  which  are  free  from  lime  are  finely 

*  May  be  artificially  obtained  in  crystals,  by  fusing  in  a  porce- 
lain crucible  an  intimate  mixture  of  1  part  of  fused  phosphate  of 
soda,  and  7  parts  of  chloride  of  lead  ;  the  mass  is  very  gradually 
heated  to  about  the  fusing-pointof  the  latter  ;  it  is  then  allowed  to 
cool,  and  the  liquid  portion  decanted  from  the  crystals. 


64  PYROMORPHITE. 

powdered,  and  dissolved  in  caustic  potassa.  The  lead 
is  precipitated  from  the  solution  by  sulphide  of  ammo- 
nium, filtered,  dried,  and  as  much  removed  from  the 
filter  as  possible.  The  filter  is  then  burned  and  the 
ashes  added  to  the  precipitate,  which  is  then  mixed 
with  a  little  sulphur,  strongly  heated  in  dry  hydrogen 
gas,  and  then  weighed  as  sulphide  of  lead. 

The  filtered  solution  is  acidified  with  hydrochloric 
acid,  which  precipitates  any  sulphide  of  arsenic,  to  be 
treated  as  directed  in  the  article  upon  copper-nickel. 
(No.  65.) 

The  liquid  filtered  from  the  sulphide  of  arsenic  is 
concentrated  by  evaporation,  supersaturated  with  am- 
monia, and  the  phosphoric  acid  precipitated  by  sulphate 
of  magnesia.  (See  No.  9.) 

The  chlorine  is  determined  in  another  portion,  by 
dissolving  in  nitric  acid,  and  precipitating  by  nitrate 
of  silver. 

For  the  determination  of  lime,  the  mineral  is  dis- 
solved in  nitric  acid,  and  the  lead  precipitated  from 
the  diluted  solution  by  sulphuretted  hydrogen.  The 
solution  filtered  from  the,sulphide  of  lead  is  neutralized 
with  ammonia,  and  the  lime  precipitated  by  oxalateof 
ammonia.  The  filtrate  is  concentrated  by  evaporation, 
mixed  with  ammonia,  and  the  phosphoric  acid  preci- 
pitated by  sulphate  of  magnesia. 

Those  specimens  which  are  free  from  lime,  but  which 
contain  arsenic  acid,  maybe  analyzed  in  the  following 
manner.  The  mineral,  in  a  state  of  very  fine  powder, 
is  digested  with  moderately  dilute  sulphuric  acid,  the 
greater  part  of  the  water  evaporated,  the  mass  mixed 
with  alcohol,  and  the  sulphate  of  lead  thrown  upon  a 
filter  and  washed  with  spirit  of  wine.  The  filtrate  is 
evaporated  to  expel  -the  alcohol,  arid  a  stream  of  sul- 
phuretted hydrogen  passed  through  it,  while  it  is 
heated  to  about  50°.  It  is  afterwards  allowed  to  cool 
while  the  gas  is  still  passing,  and,  when  saturated  with 


SILVER   AND   LEAD.  65 

sulphuretted  hydrogen,  set  aside  in  a  closed  vessel  for 
twenty-four  hours,  after  which  the  precipitated  penta* 
sulphide  of  arsenic  is  filtered  off. 

The  filtered  solution  is  treated  with  ammonia  which 
precipitates  the  iron  as  sulphide,  occasionally  mixed 
with  a  small  quantity  of  sesquioxide  of  chromium. 

The  phosphoric  acid  is  precipitated  from  the  filtrate, 
after  concentration,  by  sulphate  of  magnesia  and 
ammonia. 

In  order  to  separate  the  sesquioxide  of  chromium, 
the  mineral  is  digested  with  a  mixture  of  concentrated 
hydrochloric  acid  and  alcohol,  the  solution  filtered) 
evaporated  to  expel  the  alcohol,  and  the  sesquioxide  of 
chromium  precipitated  from  the  hot  solution  by  am*- 
monia.  It  still  contains  a  little  phosphoric  acid* 


40.  SILVER  AND  LEAD, 

I.  By  cupellation. 

II.  The  solution  of  the  two  metals  in  nitric  acid  is 
diluted  with  much  water,  heated  nearly  to  the  boiling- 
point,  and  the  silver  precipitated  as  chloride  of  silver 
by  hydrochloric  acid.     (See  No.  1.) 

The  filtered  solution  is  allowed  to  cool,  the  greater 
part  of  the  acid  neutralized  with  ammonia,  and  the  lead 
precipitated  by  sulphuretted  hydrogen.  (See  No.  39.) 

III.  The  diluted  nitric  solution  of  the  two  metals  is 
mixed  with  dilute  hydrocyanic  acid,  which  precipitates 
the  silver  as  cyanide.     When  this  has  accumulated, 
leaving  the  solution  clear,  it  is  collected  upon  a  filter 
which  has  been  dried  at  120°,  washed,  dried  at  that 
temperature,  and  weighed. 

From  the  filtrate,  after  neutralizing  the  larger  excess 
of  acid,  the  lead  may  be  precipitated  by  sulphuretted 


66  SILVER   AND   COPPER. 

hydrogen,  or  if  the  solution  be  concentrated  by  evapo- 
ration, by  sulphuric  acid  in  the  presence  of  alcohol. 

IV.  Another  method  consists  in   precipitating  the 
solution  of  the  two  rnetals  by  a  slight  excess  of  car- 
bonate  of  soda,  and   digesting   the   precipitate  with 
cyanide  of  potassium,  which  dissolves  the  silver  in  the 
form  of  a  double  cyanide,  leaving  the  carbonate   of 
lead  untouched.    Since,  however, itcontains  some  alkali, 
it  must  be  dissolved  in  nitric  acid,  and  precipitated  by 
sulphuretted  hydrogen  or  sulphuric  acid.     From  the 
solution  containing  the  silver,  the  latter  may  be  preci- 
pitated as  cyanide  by  nitric  acid. 

V.  The  solution  of  the  lead  and  silver  in  nitric  acid 
is  neutralized  with  an  akali,  mixed  with  an  akaline 
formate,  and  heated  to  boiling,  when  all  the  silver  is 
precipitated  in  the  metallic  state. 


41.  SILVER  AND  COPPER. 

(Silver-coin.) 

The  alloy  is  dissolved  in  moderately  strong  nitric 
acid,  the  silver  precipitated  from  the  hot  solution  by 
dilute  hydrochloric  acid  with  violent  agitation,  and  the 
chloride  of  silver  treated  as  in  No.  1. 

The  oxide  of  copper  is  precipitated  from  the  filtrate 
by  caustic  potassa  at  a  boiling  heat,  washed,  dried, 
ignited  and  weighed,  the  filter  being  completely  incin- 
erated apart  from  the  precipitate. 

If  the  alloy  contain  gold  also,  it  is  left  behind  by  the 
nitric  acid  as  a  brown  powder.  If  it  be  present  in 
very  small  quantities — as,  for  example,  in  all  old  silver 
coins — the  small  insoluble  residue  is  filtered  off;  thor- 
oughly washed,  the  filter  incinerated,  and  the  ash  fused 
before  the  blowpipe  with  carbonate  of  soda,  when  the 
gold  appears  in  small  globules. 


SILVER  ASSAY.  67 

When  frequent  quantitative  determinations  of  silver 
are  made,  as  in  mints,  the  test  is  made  either  by  cupel- 
lation,  which  consists  in  fusing  the  weighed  alloy  with 
several  times  its  weight  of  pure  lead  in  a  small  bone 
earth  cupel  in  a  current  of  air,  when  the  lead  and  cop- 
per are  oxidized  and  absorbed  by  the  cupel,  while  the 
pure  silver  remains  as  a  fused  button.  Or,  more  ac- 
curately, by  volumetric  analysis. 

In  order  to  prepare  pure  silver,  it  is  precipitated 
from  the  solution  by  hydrochloric  acid  or  chloride  of 
sodium,  in  the  form  of  chloride  which  is  well  washed 
and  fused  in  a  porcelain  capsule.  A  fragment  of  zinc 
is  placed  upon  the  fused  mass,  and  some  dilute  hydro- 
chloric acid  poured  over  it.  After  twenty -four  hours, 
the  chloride  of  silver  is  completely  reduced ;  the 
spongy  masses  of  silver  are  rinsed  out,  rubbed  to  a 
fine  powder  under  water,  and  digested  with  dilute 
hydrochloric  acid,  to  remove  any  zinc.  It  is  then 
thoroughly  washed  and  fused  with  borax  to  a  reguline 
mass. 

Or  the  dry  chloride  of  silver  may  be  mixed  with  an 
equal  quantity  of  anhydrous  carbonate  of  soda,  and 
the  mixture  introduced  into  a  crucible,  the  bottom  and 
sides  of  which  are  coated  with  as  thick  a  layer  as 
possible  of  carbonate  of  soda.  The  crucible  is  then 
heated  for  a  length  of  time  to  low  redness,  and  after- 
wards to  the  fusing-point  of  silver. 


42.  SILVER  ASSAY. 

From  argentiferous  galenite  tetrahedrite,  chalcopy- 
rite,  &c.,  even  when  intimately  mixed  with  gangue, 
the  whole  of  the  silver,  concentrated  in  a  small  quan- 
tity of  lead,  may  be  extracted  in  the  following  manner : 


68  GOLD  AND  COPPER. 

One  hundred  grms.  of  galenite,  finely  powdered,  are 
fused  with  30  grms.  of  nitre  and  100  grms.  of  litharge. 

Or  1  part  of  the  ore  is  fused  together  with  30  to  50 
parts  of  litharge. 

Or  1  part  of  ore  may  be  fused  with  3  parts  of  anhy- 
drous acetate  of  lead  and  2  parts  of  potashes,  under  a 
layer  of  common  salt. 

In  the  button  of  lead  obtained,  the  silver  is  deter- 
mined by  cupellation,  or  in  the  moist  way. 


43;  GOLD  AND  COPPER. 
(Coins.) 

li  The  alloy  is  dissolved  in  a  mixture  of  hydrochlo- 
ric and  nitric  acids,  care  being  taken  that  none  of  the 
latter  shall  remain  undecomposed  after  the  solution  is 
effected ;  the  liquid  is  heated  with  oxalic  acid,  which 
precipitates  all  the  gold  in  the  metallic  state.  For  the 
complete  precipitation  of  the  gold,  the  solution  must 
be  dilute,  and  not  contain  a  large  excess  of  hydrochlo- 
ric acid,  or  alkaline  chlorides.  It  is  washed,  dried, 
transferred  to  a  porcelain  crucible,  the  filter  completely 
incinerated,  and  the  gold,  together  with  the  ashes,  ig- 
nited and  weighed*  From  the  filtrate  the  copper  may 
be  precipitated  by  sulphuretted  hydrogen,  or  by  potassa 
at  a  boiling  heat. 

II.  The  gold  is  first  precipitated  by  a  solution  of 
pure  protosulphate  of  iron,  and  the  copper  is  after- 
wards separated  from  the  solution,  either  by  sulphu- 
retted hydrogen,  or  by  a  piece  of  bright  iron  placed  in 
the  liquid,  which  must  not  be  too  acid,  and  should  be 
heated  nearly  to  boiling.  The  precipitated  copper  is 
washed,  dried,  and  ignited  in  air,  when  it  is  converted 
into  oxides 


GOLD   AND   SILVER. 


44.  GOLD  AND  SILVER. 

I.  From  an  alloy  containing  less  than  about  15  per 
cent,  of  silver,  aqua  regia  dissolves  all  the  gold,  while 
the  whole  of  the  silver  is  left  as  chloride  ;  for  this  pur- 
pose, however,  the  metal  must  be  employed  in  a  very 
thinly  laminated  state.     The  solution  is  evaporated,  to 
expel  as  much  of  the  nitric  acid  as  possible;  and  di- 
luted with  water,  to  effect  the  complete  separation  of 
the  chloride  of  silver.     From  the  solution  the  gold  is 
precipitated  by  oxalic   acid,  or   by  protosulphate  of 
iron. 

II.  If  the  alloy  contain  more  than  80  per  cent,  of 
silver,  pure  nitric  acid  dissolves  the  whole  of  the  silver, 
and  leaves  the  gold.     Here  also  the  alloy  must  be  thinly 
laminated.     The  silver  is  precipitated  by  hydrochloric 
acid.     The  gold  is  well  washed,  and  dissolved  in  aqua- 
regia,  to  ascertain  if  any  trace  of  silver  be  left  in  it. 

III.  When  the  quantity  of  silver  present  in  the  alloy 
is  between  15  and  80  per  cent.,  it  cannot  be  entirely 
extracted  by  nitric  acid,  neither  can  all  the  gold  be 
dissolved  out  by  aqua  regia,  since  the  metal  becomes 
covered  with  a  thick  layer  of  chloride  of  silver.     Such 
an  alloy  should  be  fused  in  a  porcelain  crucible  with 
3  times  its  weight  of  pure  lead.     From  this  alloy,  nitric 
acid  then  dissolves  all  the  lead  and  silver,  leaving  pure 
gold. 

From  the  solution  filtered  from  the  gold,  the  silver 
is  precipitated  by  hydrocyanic  acid ;  or,  after  diluting 
largely,  and  heating  nearly  to  boiling,  by  hydrochloric 
acid. 

IV.  Silver  and  gold  in  alloys  of  these  metals  may 
also   be   separated   by    concentrated    sulphuric   acid, 
whatever  may  be  the  relative  proportion  of  the  two 
metals.     The  thinly  laminated  alloy  is  heated  with  the 
acid  in  a  capacious  dish,  until  all  evolution  of  gas 


70  AMALGAMS. 

ceases,  and  the  acid  begins  to  evaporate.  The  sulphate 
of  silver  which  is  produced  is  then  dissolved  in  the 
requisite  quantity  of  hot  water,  and  the  solution  de- 
canted from  the  gold,  which,  for  greater  certainty,  is 
once  more  heated  with  a  small  quantity  of  sulphuric 
acid ;  afterwards  thoroughly  washed,  ignited,  and 
weighed. 

Y.  All  such  alloys  may  be  also  conveniently  ana- 
lyzed by  fusion  with  bisulphate  of  potassa. 


45.  AMALGAMS. 

The  following  amalgams  may  be  analyzed  by  heating 
very  gradually  in  a  porcelain  crucible,  finally  raising 
the  heat  to  redness,  till  the  mercury  is  entirely  vola- 
tilized, and  the  tin  or  copper  oxidized.  To  insure 
complete  oxidation,  the  mass  is  ultimately  moistened 
with  concentrated  nitric  acid,  and  again  ignited.  The 
amalgam  of  silver  leaves  the  latter  in  the  metallic  state. 
In  order  to  estimate  the  mercury  also  directly,  the  fol- 
lowing method  is  adopted  : — 

I.  AMALGAM  OF  COPPER.*— The  amalgam  is  dis- 
solved in  aqua  regia,  the  solution  neutralized,  though 
not  completely,  with  potassa,  mixed  with  formate  or 
sulphite  of  potassa  or  soda,  and  allowed  to  stand  for 
some  time  at  a  temperature  between  50°  and  60°.  All 
the  mercury  is  thus  precipitated  as  subchloride. 
Above  60°,  metallic  mercury  would  also  be  separated. 
The  subchloride  of  mercury  is  collected  upon  a  filter, 

*  Tins  amalgam,  which  is  semi-fluid  at  100O,but  solid  and  crys- 
talline at  the  ordinary  temperature,  is  obtained  when  copper, 
which  has  been  precipitated  by  zinc,  is  moistened  with  nitrate  of 
suboxide  of  mercury,  and  triturated  in  a  warm  mortar  with  mer- 
cury, added  by  degrees,  until  the  amalgam  has  the  consistence  of 
butter. 


AMALGAMS.  71 

which  has  been  dried  at  100°  and  weighed,  and  its 
weight  determined  after  drying  at  100°. 

From  the  filtered  solution  the  oxide  of  copper  is  pre- 
cipitated, at  a  boiling  heat,  by  caustic  potassa. 

II.  AMALGAM  OF  TIN  (amalgam  for  mirrors). — This 
is  dissolved  in  aqua  regia,  the  solution  mixed  with  am- 
monia in  slight  excess,  afterwards  with  an  excess  of 
sulphide  of  ammonium,  and  digested  for  a  long  time 
in  a  closed  vessel.     The  bisulphide   of  tin  which  is 
formed  dissolves  in  the  sulphide  of  ammonium,  and 
the  black  sulphide  of  mercury  separates  ;  it  is  collected 
upon  a  weighed  filter,  washed  with  weak  sulphide  of 
ammonium,  and  dried  at  100°. 

From  the  solution  in  sulphide  of  ammonium  the  bi- 
sulphide of  tin  is  precipitated  by  dilute  hydrochloric 
acid,  filtered  off,  washed,  dried,  and  roasted,  together 
with  the  filter,  in  a  porcelain  crucible,  with  free  access 
of  air.  A  gentle  heat  is  at  first  applied,  which  is  gra- 
dually increased,  till  the  whole  of  the  precipitate  is 
converted  into  white  binoxide  of  tin;  a  fragment  of 
carbonate  of  ammonia  is  held  in  the  ignited  crucible  at 
the  end  of  the  operation. 

III.  AMALGAM  OF  SILVER.* — The  amalgam  is  dis- 
solved, by  the  aid  of  heat,  in  nitric  acid,  so  that  the 
solution  may  contain  the  whole  of  the  mercury  in  th<j 
state  of  protoxide;  the  acid  solution  is  diluted  with 
water,  and  the  silver  precipitated  by  an  excess  of  hy? 
drochloric  acid. 

The  mercury  in  the  filtrate  from  the  chloride  of 
silver  may  be  precipitated  by  phosphorous  acid. 

*  May  be  obtained  in  crystals  by  allowing  a  small  quantity  of 
mercury  to  remain  in  a  moderately  diluted  solution  of  nitrate  of 
silver,  or  by  placing  a  thick  bright  copper-wire  in  the  mixed  solu- 
tions of  nitrate  of  silver  and  of  subaxide  «f  mercury, 


72  TIN   AND   COPPER. 


46.  MIXTURES  OF  PROTOXIDE  OF  MERCURY, 
MINIUM,  AND  CINNABAR. 

By  digesting  with  dilute  nitric  acid,  the  protoxide 
of  mercury  is  extracted,  together  with  a  portion  of  the 
protoxide  of  lead,  the  remainder  of  the  lead  being  left 
behind  in  the  form  of  brown  binoxide,  mixed  with  the 
cinnabar.  This  residue  is  well  washed  upon  a  weighed 
filter. 

From  the  solution,  which  must  contain  an  excess  of 
nitric  acid,  the  lead  is  precipitated  by  an  excess  of  sul- 
phuric acid,  and  a  little  alcohol.  The  mercury  may 
then  be  precipitated  as  protochloride  by  hydrochloric 
acid  and  phosphorous  acid.  Before  the  separation  of 
the  lead  these  last  two  reagents  would  have  given 
chloride  of  lead  with  the  protochloride  of  mercury. 

The  mixture  of  cinnabar  and  binoxide  of  lead  is 
treated,  upon  the  filter,  with  a  warm  mixture  of  dilute 
nitric  acid  and  a  little  oxalic  acid,  which  dissolves  the 
binoxide  of  lead,  with  evolution  of  carbonic  acid.  The 
cinnabar  is  then  washed,  dried  at  100°,  and  weighed. 

The  lead  is  precipitated  from  the  solution  by  sul- 
phuric acid,  with  addition  of  some  alcohol. 

In  order  to  analyze  the  cinnabar,  it  is  dissolved  (in 
this  case,  together  with  the  filter)  in  concentrated  hydro- 
chloric acid,  with  careful  addition  of  chlorate  of  potassa ; 
the  sulphuric  acid  is  then  precipitated  from  the  diluted 
solution  by  chloride  of  barium,  the  filtrate  concentrated, 
and  the  mercury  precipitated  by  protochloride  of  tin, 
or,  better,  by  phosphorous  acid. 


47.  TIN  AND  COPPER. 
(Bronze,  Gun-metal,  Bell-metal.) 

I.  The  alloy,  as  finely  divided  as  possible,  is  oxidized 
with  concentrated  nitric  acid,  the  greater  excess  of  the 


TIN   AND  LEAD.  73 

latter  evaporated,  the  solution  diluted  with  hot  water, 
and  the  undissolved  binoxide  of  tin  filtered  off.  The 
copper  is  precipitated  from  the  filtrate  by  caustic  po- 
tassa,  at  a  boiling-heat. 

If  the  bronze  contain  also  zinc,  lead,  and  iron,  the 
lead  is  precipitated  by  sulphuric  acid,  and  the  copper 
by  sulphuretted  hydrogen.  The  solution  filtered  from 
the  sulphide  of  copper  is  heated  with  some  chlorate  of 
potassa  in  order  to  peroxidize  the  iron,  and  the  sesqui- 
oxide  of  the  latter  metal  precipitated  by  an  excess  of 
ammonia.  The  oxide  of  zinc  remains  dissolved  in  the 
alkali,  and  is  precipitated  by  sulphide  of  ammonium. 
Or  the  method  described  in  No.  31  may  be  followed. 

II.  A  surer  method  of  obtaining  the  binoxide  of  tin. 
free  from  other  metals  consists  in  oxidizing  the  alloy 
with   nitric   acid,  evaporating   to   complete   dryness, 
moistening  with  hydrochloric  acid,  and  after  some  time 
adding  water,  the  mass  dissolves  completely  and  the 
binoxide  of  tin  is  precipitated  by  sulphuric  acid.    After 
it  has  fully  settled,  it  is  filtered,  washed,  and  ignited. 

III.  A  very  accurate  analysis  may  also  be  effected 
by  heating  the  alloy  in  a  current  of  dry  chlorine,  when 
the  tin  and  a  part  of  the  iron  are  volatilized  as  chlo- 
rides, which  are  conducted  into  water,  and  chloride  of 
copper,  chloride  of  zinc,  and  chloride  of  lead  are  left. 
(See  Tetrahedrite.) 


48.  TIN  AND  LEAD. 
(Pewter,  Soft  Solder.) 

The  alloy  is  oxidized  with  moderately  strong  nitric 
acid,  which  leaves  the  tin  undissolved  in  the  form  of 
binoxide ;  after  heating  and  diluting  with  water,  the 
binoxide  of  tin  is  filtered  off,  washed,  dried,  and  ignited. 

From  the  filtrate  the  lead  is  precipitated  by  dilute 
7 


74  BISMUTH,  LEAD,  AND  TIN. 

sulphuric  acid.  The  whole  solution,  containing  the 
suspended  precipitate,  is  evaporated  to  expel  the  nitric 
acid,  until  the  sulphuric  acid  begins  to  volatilize ;  it  is 
then  diluted  with  water,  and  the  sulphate  of  lead  col- 
lected upon  a  weighed  filter,  which  has  been  dried  at 
120°,  and  washed  with  spirit  of  wine.  A  filter  which 
has  not  been  weighed  may  be  employed,  if  care  be 
taken  to  remove  as  much  as  possible  of  the  precipitate 
from  the  filter,  and  to  incinerate  the  latter  carefully 
apart,  so  that  no  reduction  of  lead  may  take  place. 
(Moreover,  see  No.  49.) 

After  the  above  operation  it  is  difficult  to  obtain  the 
binoxide  of  tin  perfectly  free  from  lead.  It  is  much 
surer  to  fuse  the  alloy  with  a  mixture  of  carbonate  of 
potassa  and  sulphur,  to  extract  the  tin  as  a  sulphide, 
and  proceed  as  in  No.  49. 


49.  BISMUTH,  LEAD,  AND  TIN. 

The  alloy  is  oxidized  with  moderately  strong  nitric 
acid,  the  mass  mixed  with  an  excess  of  ammonia  and 
sulphide  of  ammonium,  and  digested  for  some  time  in 
a  closed  flask.  In  this  way  the  tin  is  entirely  dissolved 
as  a  sulphur-salt.  The  solution  is  filtered  off  from  the 
other  sulphides,  which  are  then  washed  with  very  weak 
sulphide  of  ammonium,  and  dried. 

From  the  solution  the  bisulphide  of  tin  is  precipi- 
tated by  dilute  hydrochloric  acid,  filtered  off,  washed, 
and  dried.  It  is  then  gradually  heated,  together  with 
the  filter,  in  a  porcelain  crucible,  with  free  access  of 
air;  at  first  gently,  and  ultimately  to  redness,  so  that  it 
may  be  entirely  converted  into  binoxide  of  tin.  A 
fragment  of  carbonate  of  ammonia  is  held  in  the  cruci- 
ble at  the  end  of  the  operation,  to  remove  any  sulphuric 
acid  which  may  have  been  formed. 


75 

The  mixture  of  sulphide  of  bismuth  and  sulphide  of 
lead  is  detached,  as  far  as  possible,  from  the  filter,  the 
latter  incinerated,  and  the  ash  added  to  the  precipitate 
which  is  then  oxidized  in  a  capacious  capsule,  with  con- 
centrated nitric  acid,  a  little  sulphuric  acid  added  lest 
there  should  not  be  sufficient,  and  the  excess  of  nitric 
acid  expelled  by  heat.  The  mass  is  then  treated  with 
a  little  water,  the  solution  of  sulphate  of  bismuth  fil- 
tered off  from  the  sulphate  of  lead,  the  latter  washed 
with  water  containing  sulphuric  acid,  dried,  and  ignited. 

From  the  filtrate  the  teroxide  of  bismuth  is  precipi- 
tated by  carbonate  of  ammonia  in  excess ;  the  liquid 
is  digested  for  some  time  to  insure  the  complete  sepa- 
ration of  the  precipitate,  which  is  then  filtered  off, 
washed,  detached  as  far  as  possible  from  the  filter,  and 
ignited  in  a  porcelain  crucible,  when  it  is  converted 
into  yellow  teroxide  of  bismuth.  The  filter  is  incine- 
rated separately. 

If  the  oxide  is  fused  with  cyanide  of  potassium,  it  is 
reduced  and  determined  as  metallic  bismuth. 

The  best  method  to  separate  bismuth  from  the  other 
metals  depends  upon  this,  that  by  the  addition  of  a 
large  quantity  of  water  to  the  hydrochloric  acid  solu- 
tion, there  is  obtained  a  perfectly  insoluble  precipitate 
of  basic  chloride  of  bismuth  (2  Bi2  03+Bi2  C13),  that 
may  be  weighed  in  this  state,  or  reduced  to  a  metallic 
state,  by  fusing  with  cyanide  of  potassium.  In  order 
to  separate  the  lead,  the  concentrated  solution  is  mixed 
with  so  much  hydrochloric  acid  that  the  chloride  of 
lead  is  precipitated,  and  the  addition  of  a  few  drops  of 
water  causes  no  turbidity.  Dilute  sulphuric  acid  is 
then  added,  allowed  to  stand  for  some  time,  stirring 
occasionally,  then  mixed  with  alcohol,  well  stirred,  and 
the  sulphate  of  lead  left  to  settle  down.  It  is  then  fil- 
tered, washed  with  alcohol  containing  hydrochloric 
acid,  and  afterwards  with  pure  alcohol.  The  filtered 


76  SCHWEINFURT  GREEN1. 

solution  is  then  mixed  with  a  large  quantity  of  water, 
when  the  bismuth  is  precipitated  as  basic  chloride. 


50.  BISMUTH  AND  COPPER. 

By  carbonate  of  ammonia  bismuth  is  precipitated, 
while  copper  remains  in  solution,  but  the  separation  is 
only  approximate.  It  is  more  accurate  to  precipitate 
the  bismuth  as  basic  chloride,  as  in  No.  49. 


51.  SCHWEINFURT  GREEN. 
CuO,  A  +  3(CuO,  As03). 

When  this  substance  is  heated  with  caustic  potassa 
the  acids  are  extracted,  and  red  suboxide  of  copper 
left,  one-third  of  the  arsenious  acid  being  converted 
into  arsenic  acid. 

If  the  filtered  liquid  be  neutralized  with  nitric  acid, 
and  nitrate  of  silver  gradually  added,  a  red  brown  pre- 
cipitate of  arseniate  of  silver  is  first  produced,  and 
afterwards  a  yellow  precipitate  of  arsenite  of  silver. 

In  order  to  separate  the  two  acids,  the  solution,  pre- 
viously acidified  with  nitric  acid,  is  mixed  with  excess 
of  ammonia,  and  sulphate  of  magnesia  added,  which 
has  been  mixed  with  so  much  chloride  of  ammonium 
that  it  is  no  longer  precipitated  by  ammonia.  The 
arsenic  acid  is  thus  precipitated  by  arseniate  of  mag- 
nesia-ammonia. After  the  lapse  of  twelve  hours,  the 
precipitate  is  collected  upon  a  dried  and  weighed  fil- 
ter, washed  with  dilute  ammonia,  and  thoroughly  dried, 
at  100°.  It  then  has  the  composition  2  MgO,  NH4  O, 
AsO5-fHO,  and  contains  60.53  per  cent,  of  arsenic 
acid. — It  is  not  safe  to  ignite  this  precipitate,  since 
arsenic  is  then  liable  to  be  reduced  and  volatilized. 


ARSENIC  AND   LEAD.  77 

The  solution  filtered  from  the  magnesia-precipitate 
is  acidified  with  hydrochloric  acid,  and  the  arsenious 
acid  precipitated  as  tersulphide  of  arsenic. 

If  the  alkaline  solution  is  saturated  with  hydro- 
chloric acid,  and  heated  with  sulphurous  acid,  the 
arsenic  acid  is  reduced  to  arsenious  acid  and  may  be 
precipitated  by  hydrosulphuric  acid.  Or  if  the  solu- 
tion is  saturated  with  chlorine  gas,  all  the  arsenious 
acid  will  be  converted  into  arsenic  acid,  and  may  then 
be  precipitated  by  the  ammoniated  salt  of  magnesia.* 

If  the  original  pigment  be  digested  with  a  mixture 
of  concentrated  hydrochloric  acid  and  alcohol,  a  solu- 
tion of  chloride  of  copper  is  obtained,  and  the  arsenious 
acid  remains  behind  as  a  white  powder. 

By  long  digestion  with  an  excess  of  sulphide  of  am- 
monium, the  copper  is  separated  as  sulphide,  while  all 
the  arsenic  is  dissolved  and  may  be  precipitated  as 
tersulphide  of  arsenic  by  adding  hydrochloric  acid  to 
the  filtrate. 

When  Schweinfurt  green  is  distilled  with  dilute  sul- 
phuric acid,  the  acetic  acid  passes  over,  and  may  be 
converted  into  acetate  of  baryta  by  adding  that  base. 
The  accurate  quantitative  estimation  of  the  acetic  acid 
can  only  be  effected  by  ultimate  organic  analysis. 


52.  ARSENIC  AND  LEAD. 

The  alloy,  in  a  fine  state  of  division,  is  oxidized  with 
nitric  acid,  the  excess  of  acid  evaporated,  the  solution 
neutralized  with  ammonia,  and  the  precipitated  white 
mass  digested  for  some  time  with  an  excess  of  sulphide 
of  ammonium  in  a  closed  vessel.  The  solution  of  sul- 

*  The  detection  and  separation  of  arsenic,  see  the  following  arti- 
cle, also  poisoning  by  arsenic. 

7* 


78  ARSENIC  AND  TIN. 

phide  of  arsenic  is  filtered  from  the  sulphide  of  lead, 
which  is  collected  upon  a  weighed  filter,  washed,  first 
with  weak  sulphide  of  ammonium,  then  with  water, 
dried  and  weighed,  and  treated  as  in  No.  39. 

The  sulphide  of  arsenic  is  precipitated  from  the 
solution  by  dilute  hydrochloric  acid,  the  sulphuretted 
hydrogen  expelled  by  a  gentle  heat,  the  precipitate 
filtered  off,  washed,  and  gently  heated,  together  with 
the  filter,  in  a  beaker,  with  concentrated  hydrochloric 
acid,  with  gradual  addition  of  chlorate  of  potassa,  until 
all  the  arsenic  and  part  of  the  sulphur  are  oxidized 
and  dissolved.  The  solution  is  diluted  with  water, 
passed  through  a  filter,  which  must  be  well  washed, 
and  the  arsenic  acid  precipitated,  as  in  No.  51,  with 
sulphate  of  magnesia  and  ammonia. 


53.  ARSENIC  AND  TIN. 

The  finely-divided  compound  is  gradually  and  care- 
fully oxidized  with  nitric  acid,  which  is  dropped  upon 
it  in  a  weighed  vessel.  When  it  is  converted  into  a 
dry  white  mass,  more  nitric  acid  is  added,  and  the 
whole  evaporated  to  perfect  dryness  in  a  water-bath. 
The  mass  dried  at  100°  is  weighed.  A  portion  of  it 
is  then  weighed  in  a  bulb-tube,  one  limb  of  which  is 
bent  downwards,  and  dips  into  caustic  ammonia  con- 
tained in  a  small  flask.  A  stream  of  sulphuretted 
hydrogen  is  passed  through  the  bulb-tube,  and  when 
it  is  filled  with  gas,  the  mass  is  heated,  gently  at  first, 
afterwards  more  strongly,  until  a  sublimation  takes 
place  of  sulphide  of  arsenic  and  sulphur,  which  dissolve 
in  the  ammonia.  When  no  fresh  sublimate  is  formed, 
the  apparatus  is  allowed  to  cool,  and  the  piece  of  tube 
cut  off  in  which  any  sublimate  still  remains.  This 
tube  is  placed  in  warm  solution  of  potassa,  which  easily 


ARSENIC  AND  TIN.  79 

dissolves  the  sublimate,  the  solution  added  to  the  sul- 
phide of  ammonium,  and  the  whole  liquid  carefully 
acidified  with  hydrochloric  acid  which  precipitates  the 
sulphide  of  arsenic.  Some  powdered  chlorate  of  potassa 
is  added  to  the  liquid,  without  filtering,  and  heat  ap- 
plied till  there  remains  only  pure  sulphur,  which  is 
filtered  off.  From  the  filtrate,  the  arsenic  acid  is  then 
precipitated  by  ammonia  and  sulphate  of  magnesia  as 
in  No.  61. 

All  the  tin  is  left  in  the  bulb  in  the  form  of  dark 
brown  bisulphide  of  tin,  mixed,  however,  with  a  vari- 
able quantity  of  sulphur,  so  that  the  amount  of  tin 
cannot  be  immediately  inferred  from  the  weight  of  the 
residue.  In  order  to  determine  the  tin,  the  contents  of 
the  bulb  are  thrown  into  a  porcelain  crucible,  moistened 
with  nitric  acid,  and  ignited,  with  access  of  air,  until 
the  tin  is  entirely  converted  into  white  binoxide,  which 
is  then  weighed.  The  quantities  of  tin  and  arsenic 
are  afterwards  calculated  for  the  whole  quantity  of  the 
original  oxidized  mass. 

A  simpler  method  is  based  upon  the  solubility  of 
sulphide  of  arsenic  in  bisulphate  of  potassa,  while  the 
sulphide  of  tin  is  insoluble.  The  mass  oxidized  by 
nitric  acid  is  digested  with  a  solution  of  caustic  potash 
and  sulphur  until  it  is  completely  dissolved  (or  with 
the  exception  of  a  basic  sulphide,  from  which  it  may 
be  filtered).  The  solution  is  then  mixed  with  an  excess 
of  sulphurous  acid,  digested,  and  boiled  until  about 
two-thirds  of  the  water  has  evaporated  and  all  the  sul- 
phurous acid.  The  sulphide  of  tin  is  filtered  off  and 
washed  with  a  concentrated  solution  of  common  salt, 
and  not  with  water.  This  may  then  be  separated  from 
the  precipitate  by  a  solution  of  acetate  of  ammonia 
slightly  acid,  but  the  liquid  must  not  be  mixed  with  the 
salt  washings.  The  sulphide  of  tin  is  dried  and  con- 
verted into  the  oxide  by  roasting  in  the  air.  The 


80  TARTAR  EMETIC. 

rsenic  contained  in  the  fluid  as  arsenious  acid,  is  pre- 
cipitated by  a  stream  of  sulphuretted  hydrogen. 


54.  TARTAR-EMETIC. 
KOT,Sb0.f+2HO. 

The  powdered  salt  loses  all  its  water  at  100°. 

The  substance  is  dissolved  in  about  800  times  its 
weight  of  warm  water,  and  the  solution  saturated  with 
sulphuretted  hydrogen.  Some  hydrochloric  acid  is 
afterwards  added  to  promote  the  separation  of  the  ter- 
sulphide  of  antimony ;  when  the  liquid  has  become 
clear,  the  precipitate  is  collected  upon  a  weighed  filter, 
well  washed,  dried  at  150°,  and  weighed.  In  this  case 
the  weight  of  the  antimony  may  be  at  once  inferred 
from  that  of  the  precipitate. 

The  filtrate  is  evaporated  to  dryness,  the  saline 
residue  heated  till  the  tartaric  acid  is  completely  car- 
bonized, the  carbonaceous  mass  digested  with  dilute 
hydrochloric  acid,  filtered  off  and  thoroughly  washed. 
The  solution  is  evaporated,  and  the  residual  chloride 
of  potassium  gently  ignited  in  a  covered  crucible,  and 
weighed. 

The  amount  of  the  tartaric  acid  is  inferred  from  the 
difference.  It  can  be  directly  determined  only  by 
ultimate  organic  analysis. 


•  •  55.  ANTIMONY  AND  LEAD. 
(Type  Metal.) 

The  finely-divided  compound  is  oxidized  with  nitric 
acid,  the  solution  mixed  with  ammonia  in  slight  excess, 


ANTIMONY  AND   LEAD.  81 

and  afterwards  with  an  excess  of  yellow  sulphide  of 
ammonium,  with  which  it  is  digested  for  some  time 
until  the  precipitate  is  perfectly  black.  The  solution 
is  then  diluted  with  water,  the  sulphide  of  lead  col- 
lected upon  a  dried  and  weighed  filter,  thoroughly 
washed  with  dilute  sulphide  of  ammonium,  and  after- 
wards with  water,  dried  at  150°,  and  weighed.  (See 
No.  39.) 

The  sulphide  of  antimony  is  precipitated  from  the 
solution  by  dilute  sulphuric  acid,  and  the  liquid  ex- 
posed to  the  air  until  most  of  the  sulphuretted  hydro- 
gen has  been  dissipated.  The  precipitate  is  then 
thrown  upon  a  dried  and  weighed  filter,  well  washed, 
and  dried  at  100°  till  its  weight  is  constant. 

Since  the  quantitative  composition  of  this  precipitate 
is  not  accurately  known,  and  since,  moreover,  it  con- 
tains some  free  sulphur,  it  must  now  be  analyzed,  and 
either  the  sulphur  or  the  antimony  in  it  determined. 

To  determine  the  amount  of  sulphur  which  it  con- 
tains, a  weighed  quantity  is  detached  from  the  filter 
and  oxidized,  very  gradually  and  cautiously,  in  a  flask, 
with  concentrated  nitric  acid.  Concentrated  hydro- 
chloric acid  is  afterwards  added,  and  the  mixture  di- 
gested until  all  the  antimony  and  all  the  sulphur  are 
dissolved.  As  soon  as  this  is  the  case,  so  much  tartaric 
acid  is  added,  that  the  solution  may  be  diluted  with 
water  without  any  precipitation  taking  place.  If  any 
sulphur  should  have  been  separated  in  an  unoxidized 
state,  it  must  be  collected  upon  a  weighed  filter.  The 
sulphuric  acid  is  then  precipitated  from  the  diluted 
solution  by  chloride  of  barium,  and  the  precipitate 
washed  with  hot  water.  The  quantity  of  sulphur,  and, 
in  consequence,  that  of  the  antimony,  are  calculated 
for  the  total  weight  of  the  precipitated  sulphide  of 
antimony. 

For  the  direct  estimation  of  the  antimony,  a  weighed 
portion  of  the  original  precipitate  is  introduced  into  a 


82  BOURNONITE. 

weighed  bulb-tube,  and  heated  in  a  stream  of  hydrogen 
gas,  at  first  very  gently,  and  ultimately  to  the  fusing 
point  of  the  antimony,,  from  which  the  sulphur  is  thus 
completely  separated. 

Or,  instead  of  the  hydrogen,  a  stream  of  carbonic  acid 
gas  free  from  air  may  be  passed  through  the  tube,  and 
the  precipitate  heated  in  it  until  it  does  not  lose  any 
more  sulphur,  and  is  converted  into  black  tersulphide 
of  antimony. 

A  more  accurate  method  consists  in  converting  the 
sulphide  of  antimony  into  the  antimoniate  of  the  oxide 
of  antimony  (Sb2O3,  Sb205),  complete  oxidation  being 
produced  by  fuming  nitric  acid.  To  prevent  too  rapid 
action  it  should  be  moistened  first  with  a  few  drops  of 
weak  acid. 

The  oxidation  is  made  in  a  weighed  porcelain  cru- 
cible. By  digesting  for  some  time  the  decomposition 
is  complete,  and  the  pulverulent  precipitate  of  sulphur 
separates.  The  acid  is  then  carefully  evaporated  and 
the  residue  ignited. 


56.  BOURNONITE. 
8  Cu2S,  SbaS3  +  2  (3  PbS, 

The  powdered  mineral  is  gradually  and  carefully 
oxidized  with  concentrated  nitric  acid,  the  mass  mixed 
with  ammonia,  and  digested  for  some  time,  in  a  closed 
vessel,  with  yellow  sulphide  of  ammonium.  The  so- 
lution is  then  treated  as  directed  in  No.  55. 

The  residue  containing  sulphide  of  copper  and  sul- 
phide of  lead  is  dried  in  the  funnel,  detached  as  far  as 
possible,  from  the  filter,  the  latter  incinerated,  and  the 
sulphides  afterwards  oxidized,  in  a  dish,  by  the  gradual 
addition  of  fuming  nitric  acid.  Some  sulphuric  acid 
is  then  added,  the  whole  of  the  nitric  acid  expelled  by 


ZINKENITE.  83 

heat,  and  the  sulphate  of  copper  extracted  from  the 
mass  by  water.  The  sulphate  of  lead  is  washed,  dried, 
and  ignited.  The  oxide  of  copper  is  precipitated  from 
the  solution  by  caustic  potassa,  at  a  boiling  heat. 

This  method  is  not  quite  accurate,  since  a  little  sul- 
phide of  copper  dissolves  in  the  sulphide  of  ammonium 
together  with  the  tersulphide  of  antimony;  sulphate 
of  lead,  moreover,  is  not  quite  insoluble.  The  deter- 
mination of  the  lead  is  more  accurate  if  all  free  sul- 
phuric acid  be  expelled  by  heat  before  the  sulphate  of 
copper  is  extracted  with  water. 

A  more  exact  method  for  the  analysis  of  this  mineral 
is  that  with  chlorine,  described  in  the  article  upon 
Tetrahedrite. 


57.  ZINKENITE.* 
PbS,  Sb2S3. 

The  amount  of  sulphur  present  may  be  inferred  from 
the  loss  which  the  compound  suffers  when  heated  in  a 
bulb-tube,  through  which  a  stream  of  hydrogen  is 
passed,  when  all  the  sulphur  is  evolved  as  sulphuretted 
hydrogen,  and  PbSb  remains  behind. 

The  relative  proportions  of  lead  and  antimony  are 
determined  as  in  No.  55. 

For  the  direct  estimation  of  the  sulphur,  the  finely- 
divided  compound  is  mixed  with  3  parts  of  chlorate  of 
potassa,  and  3  parts  of  carbonate  of  soda,  and  heated 
in  a  porcelain  crucible,  at  first  gently,  and  ultimately 
to  redness,  until  the  chlorate  of  potassa  is  completely 
decomposed.  The  salts  are  then  extracted  from  the 

*  Plagionite  jamesonite,  and  feather-ore,  are  similar  combinations. 
Zinkenite  may  be  easily  prepared  artificially  by  fusing  together  7* 
parts  of  sulphide  of  lead,  with  11  parts  of  black  tersulphide  of 
antimony  iu  a  glass  tube. 


84:  RED   SILVER   ORE. 

mass  with  water,  the  residue  well  washed,  the  solution 
acidified  slightly  with  hydrochloric  acid,  and  the  sul- 
phuric acid  precipitated  by  chloride  of  barium. 


58.  BERTHIER1TE. 
FeS,  Sb2S3. 

The  mineral,  in  the  state  of  fine  powder,  is  oxidized 
with  hydrochloric  acid  and  chlorate  of  potassa,  until 
the  separated  sulphur  has  a  pure  yellow  color.  The 
solution  is  mixed  with  tartaric  acid,  and  may  then  be 
diluted  with  water  without  any  precipitation  taking 
place.  The  separated  sulphur  is  collected  upon  a  dried 
filter,  washed,  and  dried  at  100°.  The  sulphuric  acid 
produced  by  the  oxidation  is  precipitated  from  the 
solution  by  chloride  of  barium,  and  the  sulphate  of 
baryta  washed  with  hot  water. 

When  the  excess  of  baryta  has  been  removed  from 
the  filtrate  by  sulphuric  acid,  a  stream  of  sulphuretted 
hydrogen  gas  is  passed  through  the  solution,  and  the 
antimony  precipitated.  (See  also  No.  55.) 

From  the  filtered  liquid  the  iron  is  completely  oxi- 
dized and  then  precipitated  by  ammonia. 


59.  RED  SILVER-ORE.* 
Pyrargyrite,  3AgS,  Sb2S3.     Proustite,  3AgS,  As2S3. 

1.  PYRARGYRITE. — To  determine  the  amount  of  sul- 
phur, a  weighed  quantity  of  the  mineral  is  fused  in  a 

*  These  compounds  may  be  readily  obtained  artificially  by  fus- 
ing their  constituents  together.  That  which  contains  antimony  is 
prepared  by  fusing  2'2  parts  of  sulphide  of  silver  with  1  part  of 
black  tersulphide  of  antimony  in  a  crucible,  beneath  a  layer  of 


EED   SILVER  ORE. 


85 


bulb-tube,  over  a  large  spirit-lamp  or  gas-burner,  in  a 
stream  of  dry  hydrogen,  as  long  as  any  sulphuretted 
hydrogen  is  formed  ;  all  the  sulphur  is  thus  expelled, 
in  combination  with  hydrogen.  The  conclusion  of  the 
operation  is  also  indicated  by  a  sort  of  coruscation 
which  takes  place,  and  the  antimonide  of  silver  is  left  in 
the  form  of  a  perfectly  bright,  smooth,  movable  globule. 
The  tube  is  allowed  to  cool  slowly,  weighed,  and 
placed  in  communication  with  an  apparatus  for  the 
evolution  of  chlorine,  in  a  current  of  which  the  anti- 
Fig.  11. 


monide  of  silver  is  fused,  until  no  more  pentachloride 
of  antimony  is  volatilized,  and  pure  fused  chloride  of 
silver  remains.  The  latter  is  then  treated  as  in  the 
case  of  gray  copper-ore. 

The  antimonide  of  silver  may  also  be  oxidized  by 

common  salt ;  to  prepare  the  arseniferons  compound,  3  parts  of 
sulphide  of  silver  and  1  part  of  yellow  tersulphide  of  arsenic,  or 
32.4  parts  of  powdered  silver  9.6  parts  of  sulphur,  and  7.5  parts 
of  arsenic  are  fused  together  in  a  glass  tube  closed  at  one  end. 
Combination  takes  place  with  incandescence. 


86  FED  SILVER   ORE. 

nitric  acid,  and  the  silver  and  the  antimony  separated 
by  sulphide  of  ammonium,  as  in  antimonide  of  lead 
(No.  55.) 

2.  PROUSTITE. — The  light  colored  variety,  when  fused 
in  a  current  of  hydrogen,  loses  all  its  sulphur  and 
arsenic ;  but  the  complete  expulsion  of  the  latter  can 
scarcely  be  effected  in  a  glass  tube.  The  experiment 
must  be  conducted  in  a  small  porcelain  boat,  placed 
in  a  porcelain  tube.  After  a  certain  time,  the  fused 
substance  suddenly  swells  up  to  a  voluminous  bladder- 
like  mass,  from  which  the  last  portions  of  arsenic  can 
be  but  slowly  expelled. 

The  analysis  may  also  be  effected  by  dissolving  the 
red  silver-ore  in  concentrated  nitric  acid.  The  diges- 
tion is  continued  until  the  separated  sulphur  has  a  pure 
yellow  color;  the  solution  is  then  diluted  with  hot 
water,  and  filtered  from  the  sulphur,  the  total  quantity 
of  which  may  here  be  determined  from  the  loss,  unless 
it  be  directly  determined,  as  in  the  case  of  chalco- 
pyrite  (No.  30);  the  silver  is  precipitated  by  diluted 
hydrochloric  acid  (see  No.  .1),  the  solution  filtered  off, 
concentrated  by  evaporation,  with  addition  of  some 
nitric  acid  or  chlorate  of  4)otassa,  and  the  arsenic  acid 
precipitated  by  sulphate  of  magnesia.  (See  No.  51.) 

Or  the  very  finely-powdered  mineral  may  be  fused 
with  5  times  its  weight  of  a  mixture  of  equal  parts  of 
nitre  and  carbonate  of  soda  in  a  platinum  crucible,  at 
the  bottom  of  which  a  layer  of  carbonate  of  soda  has 
been  placed.  The  mass  is  afterwards  dissolved  out 
with  hot  water,  the  silver  filtered  off',  washed,  ignited 
and  weighed.  The  solution  is  acidified  with  hydro- 
chloric acid,  mixed  with  ammonia,  and  the  arsenic  acid 
precipitated  by  sulphate  of  magnesia.  The  amount 
of  sulphur  is  determined  by  loss,  unless  it  be  precipi- 
tated from  the  original  solution  in  the  form  of  sulphate 
of  baryta,  when  it  must  be  very  carefully  washed  with 


TIN  AND  ANTIMONY.  87 

hot  water  to  free  it  from  the  nitrate  of  baryta  which  it 
carries  down. 

Both  compounds  may  also  be  analyzed  with  great 
accuracy  by  means  of  chlorine  gas,  as  described  in  the 
article  upon  Grey  Copper-ore,  or  Tetrahedrite. 

In  analyzing  a  mixture  of  light  and  dark  red  silver- 
ore,  the  arsenic  and  antimony  are  separated  according 
to  the  method  described  in  No.  61. 


60.  TIN  AND  ANTIMONY. 

The  weighed  compound  is  dissolved  in  hydrochloric 
acid,  with  gradual  addition  of  nitric  acid,  and  a  piece 
of  pure  tin  placed  in  the  solution,  with  which  it  is 
heated  for  some  time,  until  the  whole  of  the  antimony 
is  precipitated  ;  the  latter  is  collected  upon  a  weighed 
filter,  washed,  dried  at  100°,  and  weighed;  the  amount 
of  tin  is  inferred  from  the  difference. 

In  order  to  determine  both  metals  directly,  the  com- 
pound, as  finely  divided  as  possible,  is  oxidized  in  a 
beaker  with  strong  pure  nitric  acid,  the  mass  evapo- 
rated to  dry  ness,  gently  ignited,  and  fused,  in  a  silver 
crucible,  with  a  large  excess  of  hydrate  of  soda.  When 
cool,  the  mass  is  treated  with  water,  rinsed  out  into  a 
beaker,  and  the  solution  mixed  with  J  its  volume  of 
strong  alcohol.  The  insoluble  antimoniate  of  soda  is 
thus  separated  from  thestannate,  carbonate,  and  excess 
of  hydrate  of  soda,  which  are  dissolved  by  the  weak 
spirit.  When  the  liquid  has  become  perfectly  clear, 
the  precipitate  is  filtered  off,  and  washed,  first  with  a 
mixture  of  equal  volumes  of  alcohol  and  water,  and 
.finally  with  strong  alcohol. 

The  alkaline  solution  is  heated  to  expel  the  alcohol, 
diluted  with  water,  acidified'with  dilute  sulphuric  acid, 
and  the  tin  precipitated  by  sulphuretted  hydrogen 


88  ARSENIC   AND   ANTIMONY. 

The  bisulphide  of  tin  is  then  converted  into  binoxide 
of  tin,  as  directed  in  No.  49. 

The  antimoniate  of  soda  is  detached  as  far  as  possible 
from  the  filter,  and  a  mixture  of  hydrochloric  and  tar- 
taric  acids  poured  over  the  latter,  and  allowed  to  flow 
into  the  beaker  containing  the  remainder  of  the  preci- 
pitate. When  the  salt  is  perfectly  dissolved,  and  the 
filter  has  been  washed,  the  antimony  is  precipitated  by 
sulphuretted  hydrogen.  The  antimony  contained  in 
the  precipitate  is  determined  as  in  No.  55. 

The  antimoniate  of  soda  may  also  be  collected  upon 
a  weighed  filter,  dried  at  100°,  and  a  weighed  portion 
mixed  with  sal-ammoniac  in  a  porcelain  crucible,  and 
ignited,  when  all  the  antimony  is  volatilized,  and  the 
salt  converted  into  chloride  of  sodium.  The  operation 
must  be  repeated  several  times  till  the  weight  is  con- 
stant, and  the  amount  of  the  antimony  may  be  calcu- 
lated from  that  of  the  chloride  of  sodium  obtained. 

Or  the  dried  antimoniate  of  soda  may  be  fused  in  a 
porcelain  crucible  with  an  excess  of  cyanide  of  potas- 
sium. The  antimony  is  reduced  and  collects  in  a 
metallic  button. 


61.  ARSENIC  AND  ANTIMONY.* 

If  only  these  two  metals  be  present,  as  in  native 
arsenic,  a  complete  separation  may  be  effected  by  heat- 
ing the  compound  in  a  bulb-tube  through  which  a 
stream  of  dry  carbonic  acid  gas  is  transmitted,  when 
the  whole  of  the  arsenic  is  volatilized,  and  the  antimony 
remains  behind.  If  too  strong  a  heat  be  applied,  a 
portion  of  the  latter  metal  may  also  be  volatilized. 

When  the  compound  under  examination  contains, 
as  is  often  the  case,  the  two  metals  in  the  form  of  sul- 

*  See  No.  132.     Poisoning  by  Arsenic. 


ARSENIC   AND   ANTIMONY.  89 

phides,  they  may  be  at  least  approximately  separated 
by  digestion  with  concentrated  hydrochloric  acid, 
which  dissolves  the  sulphide  of  antimony,  and  leaves 
that  of  arsenic,  or  with  carbonate  of  ammonia,  which 
dissolves  the  sulphide  of  arsenic. 

Methods  for  Quantitative  determination. 

I.  The  compound  is  carefully  oxidized  with  aqua- 
regia,  or  with  hydrochloric  acid  and  chlorate  of  potassa, 
some  tartaric  acid  and  a  considerable  quantity  of  chlo- 
ride of  ammonium -added,  and  the  mixture  then  treated 
with   ammonia   in   excess,  which   must  dissolve  the 
whole.     From  this  solution  the  arsenic  acid  is  precipi- 
tated by  sulphate  of  magnesia.     (See  No,  51,) 

The  filtrate  is  acidulated  with  hydrochloric  acid, 
and  the  antimony  precipitated  by  sulphuretted  hydro- 
gen, and  treated  as  in  No.  5±. 

II.  A  more  accurate  method  depends  upon  the  fact 
that  freshly  precipitated  sulphide  of  arsenic  is  soluble 
in  sulphite  of  potassa  and  sulphurous  acid,  while  the 
sulphide  of  antimony  is  not. 

The  analysis  of  commercial  gray  sulphide  of  anti- 
mony or  metallic  antimony,  is  made  in  the  following 
manner : — 

The  very  finely  pulverized  and  weighed  substance 
is  digested  with  a  solution  of  sulphide  of  potassium 
and  some  sulphur,  until  it  is  dissolved.  There  gene- 
rally remains  a  black  mixture  of  sulphides  of  lead, 
iron,  and  copper,  which  are  separated  by  filtration  and 
analyzed  by  themselves.  The  solution  is  then  mixed 
with  a  large  excess  of  a  saturated  solution  of  sulphurous 
acid  in  water,  with  this  digested  and  kept  at  the  boil- 
ing-point until  two-thirds  of  the  water  has  evaporated, 
and  all  the  sulphurous  acid  is  driven  off.  The  precipi- 
tated sulphide  of  antimony  is  filtered,  washed,  and 
treated  as  in  No.  5-1.  From  the  solution  which  contains 


90  AKSENIC,   ANTIMONY,  AND   TIN. 

the  arsenic  as  arsenious  acid,  it  is  precipitated  by  hy- 
drosulphuric  acid  as  in  No.  52. 


62.  ARSENIC,  ANTIMONY,  AND  TIN. 

The  compound  is  divided  as  finely  as  possible,  and 
carefully  oxidized  with  strong  and  pure  nitric  acid, 
the  mass  evaporated  to  dryness  and  fused  in  a  silver 
crucible  with  eight  times  its  weight  of  hydrate  of  soda, 
the  evaporating  vessel  being  previously  rinsed  with 
solution  of  soda,  which  is  added  to  the  contents  of  the 
crucible  and  evaporated  to  dryness.  The  fused  mass 
is  treated  with  hot  water,  then  diluted  with  water,  and 
one-third  its  volume  of  strong  alcohol  added.  The 
mass  is  allowed  to  stand  for  twenty-four  hours  and 
frequently  stirred ;  the  antimoniate  of  soda  is  then  fil- 
tered off,  and  washed  first  with  a  mixture  of  2  vols.  of 
water  and  1  vol.  of  alcohol,  next  with  a  mixture  of 
equal  vols.,  and  lastly  with  a  mixture  of  3  vols.  of 
alcohol  and  1  vol.  of  water,  adding  to  each  a  few  drops 
of  solution  of  carbonate  of  soda.  The  washed  salt  is 
treated  as  in  No.  60. 

The  alkaline  filtrate  is  supersaturated  with  hydro- 
chloric acid,  which  produces  a  bulky  precipitate  of 
arseniate  of  binoxide  of  tin.  Without  filtering  this  off, 
the  liquor  is  saturated  with  sulphuretted  hydrogen, 
the  precipitate  thus  converted  into  a  dark  brown  mix- 
ture of  bisulphide  of  tin  and  tersulphide  of  arsenic, 
and  the  liquor  then  allowed  to  stand  for  twenty-four 
hours  in  the  closed  vessel.  The  precipitate  is  now 
collected  on  a  weighed  filter  and  dried  at  100°.  The 
separation  of  the  tin  and  arsenic  is  effected  by  heating 
in  sulphuretted  hydrogen,  as  in  No.  53, 

A  weighed  portion  of  the  entire  precipitate  might 
also  be  jnixed  with  about  12  times  its  weight  of  a 


TETRAHEDRITE. 


91 


mixture  of  3  parts  of  carbonate  of  soda  and  1  part  of 
cyanide  of  potassium,  and  heated  in  a  covered  porce- 
lain crucible  until  all  the  arsenic  is  driven  off'.  On 
treating  the  residue  with  water,  the  tin  would  be  left 
behind  in  the  metallic  state.  Or  the  mixture  could 
be  heated  in  a  long  glass  tube,  in  a  slow  current  of 
carbonic  acid  gas,  and  thus  the  arsenic  obtained  as  a 
sublimate  in  the  tube.  In  order  to  secure  a  more 
complete  condensation,  a  weighed  coil  of  fine  sheet 
copper  could  be  introduced  into  the  tube,  and  heated 
to  ignition  at  one  place  for  the  purpose  of  forming 
arsenide  of  copper. 


63.  TETRAHEDRITE. 

4  (Cu,  Ag,  Fe,  Zn,  Hg),  +  (Sb3,  As,  Bi)2  Ss. 

Every  specimen  of  tetrahedrite  does  not  contain  all 
these   constituents;    some   of  them    may  be   entirely 

Fig.  12. 


92  TETRAHEPRITE. 

absent,  and  generally  they  may  replace  each  other  in 
the  different  kinds  in  varying  quantities. 

The  analysis  is  best  effected  by  gently  heating  the 
mineral  in  dried  chlorine  gas,  when  sulphur,  arsenic, 
antimony,  mercury,  and  a  portion  of  the  iron  are  vola- 
tilized in  the  form  of  chlorides,  and  copper,  silver,  zinc, 
and  part  of  the  iron  remain  behind,  likewise  converted 
iuto  chlorides. 

The  above  figure  shows  the  construction  of  the  ap- 
paratus to  be  used  in  such  analyses.  The  chlorine  gas, 
for  the  purpose  of  drying  it,  is  first  passed  through  a 
small  cylinder  containing  concentrated  sulphuric  acid, 
and  thence  through  the  chloride-of-calcium-tube,  which 
is  fixed  upon  a  wooden  stand. 

The  mineral,  finely  divided,  is  weighed  in  the  bulb- 
tube.  The  latter  is  best  provided  with  two  bulbs,  in 
order  to  collect  the  greater  portion  of  the  sublimate  in 
the  second  bulb,  and  thus  to  prevent  the  tube  from 
being  stopped  up. 

The  end  of  the  tube  bent  downwards  is  connected 
by  means  of  a  good  cork  or  a  caoutchouc  tube,  with 
the  three-bulb-tube  or  receiver,  hi  which  the  volatile 
products  are  to  be  condensed.  The  other  end  of  the 
latter  is  provided  with  a  small  conducting  tube,  through 
which  the  excess  of  chlorine  passes  into  a  small  flask 
containing  alcohol,  or  milk  of  lime. 

In  order  to  prevent  the  precipitation  of  antimony, 
the  three-bulb  receiver  is  not  filled  with  pure  water, 
but  with  a  mixture  of  dilute  hydrochloric  and  tartaric 
acids,  whenever  that  substance  is  present ;  the  liquid 
should  fill  about  £  of  the  two  upper  bulbs,  which  will 
require  about  50  grins.  In  this  arrangement  the  liquid 
cannot  rise  above  a  certain  point  in  either  limb,  but 
must  flow  back  again  whenever  it  has  been  raised  to  a 
certain  height. 

If  such  a  bulb-receiver  be  not  at  hand,  a  flask  with 
two  necks  may  be  used,  as  shown  in  the  annexed 


TETRAHEDRITE.  93 

figure.    The  perpendicular  limb  of  the  bulb-tube  almost 
touches  the  mixture  of  acids  in  the  receiver,  but  does 


13. 


not  dip  into  it,  because  the  liquor  might  in  that  case 
recede  into  the  bulb-tube,  the  chlorine  being  rapidly 
absorbed.  The  conducting-tube,  inserted  through  the 
second  neck,  expands  at  its  upper  portion  into  a  bulb, 
and  is  cut  off  below  in  an  oblique  direction ;  it  enters 
the  liquid  -so  far,  that  this  can  be  pressed  up  into  the 
bulb  only,  and  must  then  flow  back  again.  To  this 
tube  a  second  one  is  attached,  which  is  bent  at  a  right 
angle,  and  conducts  the  excess  of  chlorine  into  alcohol, 
or  milk  of  lime. 

It  is  advisable  not  to  connect  the  bulb-tube,  contain- 
ing the  mineral,  with  the  chlorine  apparatus,  until 
most  of  the  atmospheric  air  has  been  expelled  from  it. 

The  complete  decomposition  of  tetrahedrite  takes 
place  even  at  the  ordinary  temperature,  with  strong 
evolution  of  heat.  When  the  bulb  has  nearly  cooled 
again,  it  is  heated  gently  by  a  very  small  flame,  in 
order  to  separate  the  volatile  products  from  the  non- 
volatile, and  to  drive  the  former  into  the  second  bulb. 
It  is  scarcely  possible  to  drive  off  all  the  sesquichloride 
of  iron ;  the  heating  is  therefore  discontinued  as  soon 
as  vapors  of  this  compound  only  appear  to  be  evolved. 


94  TETRAHEDRITE. 

The  chlorine  gas  is  to  be  passed  through  in  a  gentle 
current  only,  especially  towards  the  last,  when  the  sub- 
limation is  effected,  because  otherwise  the  vapors  of 
the  volatile  products  may  pass  unabsorbed  through 
the  receiver. 

When  the  tube  has  become  clear  between  the  bulbs, 
and  the  apparatus  has  cooled,  it  is  cut  through  between 
the  bulbs  by  means  of  a  file  and  a  red-hot  coal,  and 
the  end  with  the  bulb  containing  the  sublimate  is  co- 
vered with  a  short  glass  tube,  sealed  at  one  end  and 
moistened  with  water  on  the  inside.  The  tubes  are 
allowed  to  remain  connected  in  this  manner  for  at  least 
twenty-four  hours,  in  order  to  cause  the  sublimate 
gradually  to  attract  moisture  and  to  prevent  its  becom- 
ing hot  and  thus  occasioning  loss  on  being  afterwards 
dissolved  in  water,  as  would  otherwise  be  the  case.  It 
is  then.dissolved  in  a  little  water,  to  which  some  hy- 
drochloric and  tartaric  acids  have  been  added,  the  tube 
is  carefully  rinsed,  and  the  rinsings  added  to  the  solu- 
tion in  the  receiver.  Should  the  liquid  be  cloudy,  in 
consequence  of  a  separation  of  antimonious  acid,  a 
gentle  heat  must  be  applied,  in  order  to  redissolve  the 
latter.  In  case  of  sulphur  having  separated  in  an  un- 
oxidized  state,  it  must  be  filtered  off. 

I.  ANALYSIS  OF  THE  FIXED  EESIDUE. — The  bulb 
containing  it  is  placed  in  a  beaker  with  dilute  hydro- 
chloric acid,  and  digested  until  the  contents  are  dis- 
solved, with  the  exception  of  the  chloride  of  silver. 
This  is  filtered  off  and  treated  as  in  No.  1.  Should 
chloride  of  lead  be  present,  as  is  the  case  in  the  analysis 
of  bournonite,  it  must  be  dissolved  by  using  a  larger 
quantity  of  water.  In  this  case  the  contents  of  the 
bulb  have  to  be  heated  very  cautiously,  that  the  chlo- 
ride of  lead  may  not  volatilize. 

A  slow  current  of  sulphuretted  hydrogen  is  then 
passed  through  the  solution  until  it  is  completely  satu- 


TETRAHEDRITE.  95 

ratecT.     The  precipitated  sulphide  of  copper  is  treated 
as  in  No.  30,  or,  if  lead  be  present,  as  in  No.  56. 

The  solution  filtered  off  from  the  precipitate  contains 
part  of  the  iron,  and  if  too  great  a  heat  was  avoided, 
all  the  zinc;  it  is  then  heated  to  ebullition, and  mixed 
with  some  chlorate  or  hypochlorite  of  an  alkali,  in 
order  to  convert  the  former  metal  into  a  higher  oxide; 
the  iron  and  zinc  are  then  separated  and  determined 
as  in  No.  31. 

II.  ANALYSIS  OF  THE  VOLATILE  PRODUCTS. — This 
solution  contains  the  mercury,  antimony,  arsenic,  a 
portion  of  the  iron,  and  the  sulphur,  partly  in  the  form 
of  sulphuric  acid,  partly  unoxidized. 

The  sulphuric  acid  can  be  precipitated  with  chloride 
of  barium,  and  the  excess  of  baryta  again  removed  by 
sulphuric  acid. 

It  is,  however,  much  more  convenient  to  determine 
the  amount  of  sulphur  in  a  separate  'portion  of  the 
mineral.  For  this  purpose  it  is  finely  divided,  mixed 
with  three  times  its  weight  of  finely-powdered  chlorate 
of  potassa  and  then  with  as  much  of  dry  carbonate  of 
soda,  and  the  mixture  very  gradually  heated  in  a  pla- 
tinum crucible  (the  bottom  of  which  is  previously 
covered  with  carbonate  of  soda,  as  a  precaution)  until 
all  the  chlorate  of  potassa  is  decomposed.  When  cold, 
the  mass  is  treated  with  water,  the  solution  filtered, 
slightly  acidulated  with  hydrochloric  acid,  and  the 
sulphuric  acid  precipitated  by  chloride  of  barium  as 
in  No.  3. 

For  the  determination  of  the  other  constituents,  the 
solution  of  the  volatile  chlorides  is  heated  to  about  60° 
and  then  a  gentle  current  of  sulphuretted  hydrogen 
passed  through  it  until  it  is  cold.  When  completely 
saturated  with  sulphuretted  hydrogen,  the  solution  is 
allowed  to  stand  for  twelve  hours,  and  then  the  pre- 
cipitate, which  consists  of  the  sulphides  of  mercury, 
antimony,  and  arsenic;  collected  on  a' filter  which  has 


96  TETRAHEDRTTE. 

been  dried  and  weighed.  After  being  washed  with 
sulphuretted- hydrogen  water,  the  precipitate  is  removed 
from  the  filter,  taking  care  not  to  damage  the  latter ; 
it  is  washed  off  as  well  as  possible,  and  a  concentrated 
solution  of  sulphide  of  ammonium  poured  upon  it,  with 
which  it  is  digested  in  a  closed  vessel  until  the  whole 
of  the  sulphides  of  arsenic  and  antimony  are  dissolved, 
and  the  sulphide  of  mercury  has  assumed  a  pure  black 
color.  When  completely  cold,  it  is  again  collected  on 
the  filter  previously  used,  washed  first  with  dilute  sul- 
phide of  ammonium,  and  towards  the  end  with  pure 
water,  dried  and  weighed. 

From  the  solution  in  sulphide  of  ammonium,  the 
sulphides  of  arsenic  and  antimony  are  precipitated  by 
an  excess  of  dilute  sulphuric  acid,  and  separated  and 
determined  as  in  No.  61. 

From  the  liquid  which  has  been  filtered  off  from 
the  precipitate  by  sulphuretted  hydrogen,  the  iron  can 
only  be  separated  by  sulphide  of  ammonium  after 
neutralizing  with  ammonia,  on  account  of  the  presence 
of  tartaric  acid.  When  the  sulphide  of  iron  is  com- 
pletely separated  by  digestion  at  a  gentle  heat,  it  is 
filtered  off)  and  washed  with  sulphuretted  hydrogen- 
water;  the  filter  is  then  put  into  a  beaker,  and  digested 
with  hydrochloric  acid  until  all  the  sulphide  of  iron 
is  dissolved.  The  solution  is  then  filtered  off  from  the 
paper,  the  latter  washed,  the  liquid  heated  with  chlo- 
rate of  potassa,  and  the  sesqui  oxide  of  iron  precipitated 
by  ammonia. 

Or  the  sulphide  of  iron  is  dried,  removed  from  the 
filter,  which  is  burned,  and  the  ashes  added  to  the  pre- 
cipitate, with  a  small  piece  of  sulphur,  and  strongly 
ignited  in  a  stream  of  dry  hydrogen.  It  is  weighed 
as  Fe  S — sulphide  of  iron. 

If  the  amount  of  sulphide  of  iron  be  but  small,  the 
filter  is  ignited  with  the  precipitate,  the  air  having 


GERMAN   SILVER.  97 

free  access,  until  all  the  iron  is  converted  into  sesqui- 
oxide,  and  its  weight  remains  constant. 


64.  GERMAN  SILVER  (ARGENTAN). 
(Cu,  Ni,  Zn). 

The  alloy  is  dissolved  in  nitric  acid,  the  greater 
excess  of  acid  evaporated,  the  solution  diluted  with 
water,  and  the  copper  precipitated  by  means  of  sul- 
phuretted hydrogen.  (See  No.  30.) 

The  filtered  liquor  is  concentrated  by  evaporation, 
precipitated  by  an  excess  of  solution  of  potassa,  and 
heated  with  it,  when  the  protoxide  of  nickel  is  sepa- 
rated and  the  oxide  of  zinc  dissolved.  From  this  solu- 
tion the  latter  is  precipitated  by  sulphide  of  potassium, 
or,  after  being  saturated  with  hydrochloric  acid,  by 
carbonate  of  soda  at  a  boiling  heat. 

In  this  manner,  however,  the  oxides  of  nickel  and 
zinc  cannot  be  separated  with  precision;  some  oxide 
of  zinc  remains  with  the  protoxide  of  nickel. 

The  separation  is  also  effected  incompletely  by  fusing 
the  mixture  of  the  oxides  with  hydrated  potassa,  or  by 
precipitating  both  oxides  with  carbonate  of  soda  at  a 
boiling  heat,  converting  the  protoxide  of  nickel  into 
black  sesquioxide  by  digestion  with  hypochlorite  of 
soda,  and  then  extracting  the  oxide  of  zinc  by  means 
of  caustic  potash,  or  the  solution  is  mixed  with  acetate 
of  soda  and  sulphuretted  hydrogen  passed  into  it.  At 
first  white  sulphide  of  zinc  is  precipitated,  and  by  de- 
grees the  black  sulphide  of  nickel.  A  more  accurate 
result  is  obtained  if  the  mixture  of  both  oxides  is 
mixed  with  3  times  its  weight  of  carbonate  of  potassa 
and  the  same  quantity  of  sulphur,  carefully  fused  to- 
gether in  a  porcelain  crucible,  until  it  flows  quietly, 
and  when  cool  the  alkaline  sulphide  extracted  with 
9 


98  N1CCOLITE. 

water.  Dilute  hydrochloric  acid  is  then  poured  upon 
the  sulphides  of  the  metals,  which  dissolves  only  the 
sulphide  of  zinc. 

The  most  accurate  method  for  the  separation  of  the 
three  metals  consists  in  dissolving  the  German  silver 
in  hydrochloric  acid,  adding  nitric  acid,  drop  by  drop, 
and  saturating  the  solution,  which  must  not  be  too 
acid,  with  sulphurous  acid,  and  precipitating  the  cop- 
per as*subsulpho-cyanide.  (See  No.  33.)  The  filtered 
solution  is  then  evaporated  to  a  small  volume,  mixed 
with  an  excess  of  caustic  potassa,  and  gradually  with 
hydrocyanic  acid,  until  the  precipitate  is  completely 
dissolved,  and  is  of  a  yellow  color.  From  this  solu- 
tion of  double 'cyanides  the  zinc  may  be  precipitated 
as  a  sulphide,  by  sulphide  of  potassium,  and  not  sul- 
phide of  ammonium.  After  digestion  by  itself  for 
some  hours,  at  a  gentle  heat,  it  is  filtered.  The-  solu- 
tion is  then  boiled  with  fuming  nitric  and  hydrochloric 
acids,  or  in  place  of  the  latter,  chlorate  of  potassa,  and 
the  protoxide  of  nickel  precipitated  while  hot,  by 
caustic  potassa.  It  is  then  dried  and  ignited. 


65.  NICCOLITE.* 

NiAs. 

I.  PREPARATION  OF  PURE  NICKEL. — The  finely 
powdered  arsenide  of  nickel  is  heated  in  a  crucible 
placed  obliquely  in  the  fire  where  the  draught  is 
strong  to  carry  off  the  fumes,  and  roasted  at  a  gentle 
heat  with  continual  stirring,  until  the  vapors  of  arsenic 
cease  to  be  given  off,  and  it  is  changed  into  greenish 
basic  arsenate  of  nickel. 

*  Arsenide  of  nickel,  with  a  varying  amount  of  cobalt  and  iron. 
The  smelting-products,  known  by  the  name  of  cobalt-  and  nit-kel- 
speiss,  have  a  similar  composition,  and  contain  besides  frequently 
accidental  admixtures  of  copper  and  bismuth. 


NICCOLITE.  99 

II.  Or  the  powdered  ore  is  mixed  with  2  parts  of 
dry  soda,  and  2  of  saltpetre,  in  a  clay  crucible,  and 
ignited  for  a  considerable  time.     After  the  mass  has 
cooled,  all  the  arsenate  of  potassa  is  extracted  by  hot 
water,  and  the  remaining  oxide  washed. 

III.  Or  the  ore  is  mixed  with  2  parts  of  dry  soda 
and  If  parts  of  sulphur,  in  a  clay  crucible,  and  gradu- 
ally heated  to  redness.     It  is  kept  at  a  low  red  heat  for 
some  time,  being  well  covered.     The  sulph-arsenate 
and  sulphide  of  sodium  are  extracted  by  water,  after 
the  mass  has  cooled,  and  the  crystalline  sulphide  of 
nickel  washed  by  decantation. 

The  mixture  of  oxides  remaining  behind  in  the 
first  and  second  cases  is  dissolved  in  hot  concentrated 
hydrochloric  acid,  that  of  the  sulphides,  in  the  third 
case,  in  hydrochloric  acid  with  gradual  addition  of 
nitric  acid  and  with  application  of  heat. 

The  solution  is  heated  to  about  70°,  and  during  that 
time,  and  until  it  has  cooled,  saturated  with  sulphuret- 
ted hydrogen;  it  is  then  allowed  to  stand  in  a  closed 
vessel  for  twenty-four  hours,  when  copper,  bismuth, 
and  a  residue  of  arsenic  are  precipitated. 

The  arsenic  is  more  easily  precipitated  if  first  con- 
verted into  arsenious  acid  by  heating  with  sulphurous 
acid.  The  solution  must  be  freed  from  an  excess  of 
sulphurous  acid  by  boiling,  before  the  sulphuretted 
hydrogen  is  passed  into  it. 

The  sulphuretted  hydrogen  having  been  expelled 
by  heat,  the  solution  is  filtered,  heated  to  boiling,  and 
precipitated  by  carbonate  of  soda;  the  precipitate, 
containing  all  the  nickel,  cobalt,  and  iron,  is  thoroughly 
washed. 

It  is  then,  whilst  still  moist,  treated  and  digested 
with  an  excess  of  a  hot  saturated  solution  of  oxalio 
acid,  when  all  the  iron  is  dissolved,  and  the  nickel  and 
cobalt  are  left  in  the  form  of  oxalates.  They  are 


100  NICCOLITE. 

filtered  off,  washed,  and  digested  with  concentrated 
caustic  ammonia  until  they  are  dissolved. 

The  blue  solution  is  then  set  aside  in  an  open  vessel 
until  all  the  free  ammonia  has  evaporated  (under  a 
bell-jar  over  sulphuric  acid,  so  that  the  ammonia  may 
not  all  be  lost),  during  which  time  the  nickel  separates 
in  the  form  of  green  oxalate  of  protoxide  of  nickel 
and  ammonia,  whilst  the  cobalt  remains  in  the  solution 
to  which  it  imparts  a  red  color. 

The  nickel-salt  is  filtered  off,  washed,  and  ignited  in 
a  closed  crucible  or  in  a  glass  tube,  when  pure  metallic 
nickel  remains  behind. 

The  cobalt  may  be  obtained  from  the  solution  by 
evaporation  and  ignition  of  the  residue,  or  by  boiling 
it  with  caustic  potassa  until  no  farther  disengagement 
of  ammonia  takes  place ;  or  when  smaller  quantities 
are  operated  upon,  by  an  alkaline  sulphide,  and  subse- 
quent addition  of  dilute  sulphuric  acid  in  order  to 
separate  the  sulphide  of  cobalt.  It  however  still  con- 
tains nickel. 

The  pure  metal  may  be  easily  prepared  from  com- 
mercial nickel  by  dissolving  it  in  hydrochloric  acid 
with  the  addition  of  some  nitric  acid,  purifying  the 
solution  by  sulphuretted  hydrogen,  and  then  precipi- 
tating nickel  and  cobalt  by  the  addition  of  a  boiling 
saturated  solution  of  binoxalate  of  potassa.  The 
washed  precipitate  is  then  ignited,  the  metal  dissolved 
in  hydrochloric  with  nitric  acid  and  cobalt  and  nickel 
separated  by  nitrite  of  potassa. 

For  the  purpose  of  separating  the  iron,  the  solution, 
after  being  again  oxidized,  may  also  be  mixed  with 
chloride  of  ammonium,  and  then  with  ammonia  in 
excess,  when  sesquioxide  of  iron  (with  a  little  nickel 
and  cobalt)  is  precipitated,  whilst  nickel  and  cobalt 
remain  in  solution. 

II.  QUANTITATIVE  ANALYSIS. — The  very  finely- 
powdered  arsenide  of  nickel  is  fused  with  2  parts  of 


NICCOLITE.  101 

nitrate  of  potassa  and  2  parts  of  carbonate  of  soda,  in 
a  platinum  crucible,  the  bottom  and  sides  of  which 
have  previously  been  carefully  covered  with  carbonate 
of  soda;  the  mass  is  then  ignited  for  some  time,  and 
when  cold  is  digested  with  water ;  the  oxides  formed 
are  filtered  off  and  thoroughly  washed. 

The  solution  contains  all  the  arsenic  in  the  form  of 
arsenates  of  the  alkalies;  it  is  supersaturated^  with 
hydrochloric  acid,  and  then  mixed  with  concentrated 
caustic  ammonia  and  sulphate  of  magnesia. 

After  twenty-four  hours  the  precipitate  is  collected 
on  a  weighed  filter,  washed  with  dilute  caustic  am- 
monia, dried  at  100°  and  weighed.  (See  No.  51.) 

The  arsenic  may  also  be  determined  from  the  loss. 

The  oxides  are  dissolved  in  concentrated  hydro- 
chloric acid,  and  the  copper  and  bismuth  precipitated 
from  the  solution  by  sulphuretted  hydrogen.  The 
precipitate  is  treated  as  in  No.  50. 

The  liquid  filtered  off  from  the  precipitate  is  heated 
nearly  to  boiling,  and  mixed  with  some  chlorate  of 
potassa  in  order  to  peroxidize  the  iron,  which  may 
then  be  separated  from  the  nickel  and  cobalt  in  the 
same  manner  as  from  manganese,  either  by'succinate 
of  ammonia  or  by  carbonate  of  baryta.  (See  No.  25.) 

From  the  liquid  filtered  off  from  the  succinate  of 
iron,  nickel  and  cobalt  are  precipitated  at  a  boiling- 
heat  by  caustic  potassa,  filtered  off,  and  washed  witk 
hot  water. 

From  the  liquid  separated  from  the  carbonate  of 
baryta,  the  dissolved  baryta  is  precipitated  by  sul- 
phuric acid,  and  the  nickel  and  cobalt  are  then  pre- 
cipitated from  the  hot  solution  by  caustic  potassa. 

The  precipitate  containing  the  hyd rated  oxides  of 
nickel  and  cobalt  is  gradually  mixed,  whilst  still  moist, 
with  dilute  hydrocyanic  acid  and  solution  of  potassa 
(or  cyanide  of  potassium),  and  a  gentle  heat  applied 
until  it  is  dissolved.  The  yellowish-red  solution  is 


. 

102  NICCOLITE. 

heated  to  boiling,  in  order  to  expel  the  excess  of  the 
hydrocyanic  acid  and  to  convert  the  cyanide  of  cobalt 
and  potassium  into  the  cobalticyanide,  and  is  then 
mixed,  whilst  still  warm,  with  levigated  protoxide  of 
mercury.  By  this  treatment  the  cyanide  of  nickel  and 
potassium  is  decomposed  and  all  the  nickel  precipi- 
tated, partly  in  the  form  of  oxide,  partly  as  cyanide, 
whilst  mercury  takes  its  place. 

The  precipitate,  when  washed  and  ignited  with  access 
of  air,  leaves  pure  oxide  of  nickel  behind. 

If  the  mixture  of  both  oxides,  previously  to  the 
treatment  with  hydrocyanic  acid  and  potassa,  have 
been  dried  and  reduced  to  metal  by  igniting  it  in  a 
current  of  hydrogen  (and  the  metal  weighed),  the 
amount  of  cobalt  need  not  now  be  determined  directly. 

If  this  be  not  the  case,  the  solution  which  still  con- 
tains the  cobalt  is  carefully  neutralized  with  nitric 
acid,  and  solution  of  nitrate  of  suboxide  of  mercury, 
as  neutral  as  possible,  added,  as  long  as  it  produces  a 
white  precipitate  of  cobalticyanide  of  mercury.  After 
being  washed  and  dried,  the  precipitate  is  ignited  with 
access  of  air,  when  it  is  converted  into  black  oxide  of 
cobalt,  which,  after  being  weighed,  must  be  reduced 
by  strong  ignition  in  a  current  of  hydrogen,  on  account 
of  its  amount  of  oxygen  varying  according  to  the  tem- 
perature. 

When  the  nickel-speiss  contains  lead  and  sulphur, 
the  same  method  is  used  which  has  been  given  for  the 
analysis  of  tetrahedrite,  where  the  compound  is  decom- 
posed by  heating  it  in  a  current  of  dry  chlorine  gas. 

Another  good  method  of  separation  of  nickel  from 
cobalt  is  the  following :  the  solution  of  both  oxides  is 
made  as  concentrated  as  possible,  and  neutralized  with 
potassa,  mixed  with  a  concentrated  solution  of  nitrite 
of  potassa,  acidified  with  acetic  acid  and  allowed  to 
stand  for  twenty-four  hours.  The  yellow  precipitate  of 
nitrite  of  sesquioxide  of  cobalt  and  potassa  (Cos03, 


SMAtTITE.  103 

3  KO,  5N03  HO)  is  filtered,  washed  with  a  solution  of 
chloride  of  potassium,  dissolved  in  hydrochloric  acid 
and  the  protoxide  of  cobalt  precipitated  by  caustic 
potassa.  Protoxide  of  nickel  may  be  precipitated 
from  the  filtered  solution  in  the  same  manner. 

If  nickel  is  to  be  precipitated  from  a  solution  by 
means  of  sulphide  of  ammonium,  it  is  not  complete, 
leaving  sulphide  of  nickel  undissolved,  giving  a  brown 
color,  if  the  sulphide  of  ammonium  does  not  contain, 
by  means  of  oxidation,  a  higher  sulphide. 

The  best  method  is  to  saturate  the  nickel  solution 
with  sulphuretted  hydrogen,  and  drive  off  so  much 
ammonia  that  the  solution  is  feebly  alkaline.  Then 
filter  as  quickly  as  possible,  and  wash  the  precipitate 
with  water  containing  sulphuretted  hydrogen. 


66.  SMALTITE. 
Speiss  Cobalt.* 
(Co,  Fe,  Ni)  As2. 

The  analysis  and  the  preparation  of  pure  cobalt  can 
be  effected  by  the  same  process  as  the  analysis  of  cop- 
per-nickel and  the  preparation  of  pure  nickel. 

Since  the  arsenide  of  cobalt  contains  upwards  of  70 
per  cent,  of  arsenic,  it  is  advisable  to  remove  a  great 
portion  by  first  fusing  it  with  common  salt,  and  after- 
wards roasting  or  fusing  it  with  a  mixture  of  soda  and 
sulphur. 

It  may  be  separated  from  nickel  by  nitrite  of  potassa. 
For  the  preparation  of  fused  metallic  cobalt,  the  yellow- 
precipitate  is  dissolved  in  the  smallest  possible  quan- 
tity of  hydrochloric  acid,  the  solution  mixed  with 

*  Arsenide  of  cobalt,  with  small  quantities  of  nickel,  iron,  and 
copper. 


lOi  COBALTITE. 

acetate  of  soda,  and  the  pale  rose-red  oxide  of  cobalt 
precipitated  by  a  hot  saturated  solution  of  oxalic  acid. 
The  yellow  salt  may  also  be  changed  directly  to  an 
oxalate  by  boiling  with  oxalic  acid.  After  it  is 
washed  and  dried,  it  is  placed  in  an  unglazed  porcelain 
crucible,  standing  in  a  Hessian  crucible,  pressed  in 
firmly,  both  crucibles  covered  and  luted,  and  then 
placed  in  a  strong  blast  or  furnace  fire. 

The  cobalt  may  also  be  separated  from  the  nickel, 
if  the  solution  mixed  with  hydrochloric  acid  is  con- 
siderably concentrated  by  evaporation,  mixed  with 
sal-ammoniac  and  ammonia  in  excess,  and  the  brown 
solution  allowed  to  stand  exposed  to  the  air  until  it 
has  acquired  a  fine  purple  tint.  If  it  be  now  saturated 
with  hydrochloric  acid  and  heated  to  boiling,  the 
greater  portion  of  the  cobalt  separates  in  the  form  of 
a  carmine  crystalline  powder,  which  appears  to  be 
5NH3-f  CojjCly  and  when  ignited  leaves  protochloride 
of  cobalt. 

If  dissolved  in  boiling  dilute  hydrochloric  acid,  this 
compound  crystallizes  in  dark  red  octahedral  crystals. 
Heated  alone  blue  chloride  of  cobalt  is  formed,  in 
hydrogen  gas,  metallic  cobalt. 


67.  COBALTITE. 
CoS2+CoAs2. 

I.  The  finely-powered  mineral  is  decomposed  by 
heating  it  in  a  current  of  dry  chlorine-gas,  as  in  the 
analysis  of  tetrahedrite,  when  the  cobalt  remains  be- 
hind in  the  form  of  protochloride,  whilst  arsenic  and 
sulphur  are  obtained  as  acids,  dissolved  in  the  water 
of  the  receiver.  The  protochloride  of  cobalt  can  then 
immediately  be  reduced  to  metal,  in  the  same  tube,  by 
heating  it  in  hydrogen,  and  weighed,  if  the  determina- 


COBALTITE.  105 

tion  of  the  small  amount  of  iron  contained  in  it  be 
neglected ;  or  it  is  dissolved  in  water  acidulated  with 
hydrochloric  acid,  and  the  solution  precipitated  at  a 
boiling  heat  by  caustic  potassa.  The  small  amounts 
of  nickel  and  iron  contained  in  the  oxide  of  cobalt 
are  then  determined  as  in  No.  66. 

The  sulphuric  acid  is  determined  by  means  of  chlo- 
ride of  barium,  and  the  excess  of  baryta  removed  by 
sulphuric  acid.  The  filtered  solution  is  concentrated 
by  evaporation,  and  the  arsenic  acid  precipitated  by 
sulphate  of  magnesia  and  ammonia  as  in  No.  65. 

II.  The  mineral  is  dissolved  in  concentrated  hydro- 
chloric acid,  with  gradual  addition  of  nitric  acid,  until 
it  is  completely  dissolved,  or  the  undissolved  sulphur 
is  left  behind  with  a  fine  yellow  tint.  The  latter  is 
then  collected  on  a  weighed  filter,  dried  at  100°  and 
weighed. 

From  the  solution  the  sulphuric  acid  is  precipitated 
by  chloride  of  barium,  and  the  amount  of  sulphur 
calculated  from  the  precipitate,  is  added  to  that  directly 
determined. 

The  excess  of  baryta  is  removed  from  the  solution 
by  sulphuric  acid. 

The  filtrate  is  mixed  with  sulphurous  acid,  allowed 
to  stand  for  twenty-four  hours,  then  heated  to  boiling 
until  the  excess  of  sulphurous  acid  is  completely  driven 
off",  and  when  cooled  down  to  about  50°,  saturated  with 
sulphuretted  hydrogen.  Thus  saturated,  it  is  left  to 
stand  for  twenty-four  hours,  the  sulphuretted  hydrogen 
removed  by  gentle  evaporation,  and  the  sulphide  of 
arsenic  collected  on  a  weighed  filter  and  dried  at  100°. 
It  is  then  treated  as  in  No.  52. 

The  solution  of  cobalt  filtered  from  this  precipitate 
is  heated  to  boiling,  mixed  with  a  little  chlorate  of 
potassa,  in  order  to  bring  the  iron  to  a  higher  state  of 
oxidation,  carefully  neutralized  with  carbonate  of  soda, 


106  COBALTITE. 

acetate  of  soda  added  and  heated  to  boiling,  which  pre- 
cipitates the  iron  free  from  cobalt.* 

The  protoxide  of  cobalt  is  precipitated  from  the  fil- 
tered solution  at  a  boiling  heat  by  means  of  caustic 
soda,  washed  with  hot  water,  ignited,  and  reduced  in 
a  current  of  hydrogen  at  as  high  a  temperature  as 
possible.  When  moistened  with  water  after  being 
weighed,  the  metal  must  not  exhibit  an  alkaline  reac- 
tion. Any  nickel  present  may  be  determined  as  in 
No.  65. 

III.  The  mineral  is  fused  with  carbonate  of  soda 
and  saltpetre  as  in  the  analysis  of  copper-nickel,  No. 
65.  The  mass  is  then  treated  with  warm  water,  and 
the  black  oxide  of  cobalt  filtered  off.  The  solution  is 
slightly  acidified  with  hydrochloric  acid  and  the  sul- 
phuric acid  precipitated  by  chloride  of  barium.  After 
the  excess  of  baryta  has  been  removed  by  sulphuric 
acid,  the  solution  is  concentrated  by  evaporation,  mixed 
with  sal-ammoniac  and  sulphate  of  magnesia,  and  the 
arsenic  acid  precipitated  by  ammonia. 

The  oxide  of  cobalt  is  dried,  the  filter  incinerated, 
the  ash  added  to  the  oxide,  and  the  whole  dissolved  in 
concentrated  hydrochloric  acid.  The  sesquioxide  of 
iron  is  then  precipitated,  by  means  of  succinate  of  soda, 
from  the  dilute  solution,  after  carefully  neutralizing 
with  carbonate  o£  soda;  and  the  cobalt  and  nickel 
separated  as  above. 

The  sesquioxide  of  iron  cannot  be  precipitated,  in 
this  case,  by  carbonate  of  baryta,  because  some  oxide 
of  cobalt  is  precipitated  at  the  same  time  ;  neither  does 
the  precipitation  by  an  excess  of  ammonia  lead  to 
exact  results,  on  account  of  some  oxide  of  cobalt  remain- 
ing combined  with  the  sesquioxide  of  iron. 

An  approximate  separation  of  both  oxides  may  also 

*  From  a  solution  of  nickel,  iron  thus  precipitated  always  con- 
tains some  of  the  nickel. 


MANGANESE   AND   COBALT,    OR   NICKEL.          107 

be  effected  by  neutralizing  the  solution  with  ammonia, 
precipitating  both  metals  by  sulphide  of  ammonium, 
and  then  adding  a  slight  excess  of  dilute  hydrochloric 
acid,  when  sulphide  of  iron  is  dissolved  and  sulphide 
of  cobalt  is  left  undissolved. 

Or  both  oxides  are  precipitated  by  caustic  potassa, 
the  precipitate  washed,  removed  from,  the  filter,  and 
the  latter  carefully  cleansed  with  water  from  the  wash- 
ing-bottle ;  the  mass  is  then  mixed  with  a  slight  excess 
of  powdered  oxalic  acid,  when  the  oxide  of  cobalt  is 
converted  into  rose-colored,  insoluble  oxalate,  whilst 
the  sesquioxide  of  iron  is  dissolved.  After  twenty-four 
hours  the  former  is  collected  on  a  weighed  filter,  washed 
with  cold  water,  dried  at  100°,  and  a  weighed  portion 
of  it  ignited  in  a  glass  tube,  one  end  of  which  is  sealed, 
whilst  the  other  is  drawn  out  into  a  point;  by  this  pro- 
cess the  oxalate  of  cobalt  is  reduced  to  metal.  Whilst 
the  tube  is  still  red-hot  the  point  is  sealed  with  the 
blow-pipe,  and  the  tube  weighed  when  cold. 


68.  MANGANESE  AND  COBALT,  OR  NICKEL.* 

For  the  merely  approximate  separation,  the  oxides 
are  precipitated  by  carbonate  of  soda,  the  precipitate 
dissolved  in  an  excess  of  acetic  acid  and  the  cobalt  or 
nickel  precipitated  from  the  solution  by  sulphuretted 
hydrogen,  when  manganese  remains  dissolved.  The 
solution  of  the  chlorides  or  of  the  sulphates  may  also 
be  mixed  with  acetate  of  soda,  and  the  nickel  or  cobalt 
precipitated  by  sulphuretted  hydrogen. 

Or  the  solution  is  mixed  with  considerable  chloride 

*  Black  cobalt-ore  (earthy  ore  of  cobalt)  is  a  compound  of  prot- 
oxide of  cobalt  with  binoxide  of  manganese.  Moreover,  almost 
every  variety  of  manganese-ore  contains  small  quantities  of  cobalt 
for  the  detection  of  which  the  residues  of  the  preparation  of  chlo- 
rine may  be  used. 


108          MANGANESE  AND   COBALT,    OR  NICKEL. 

of  ammonium,  saturated  with  ammonia,  and  the  man- 
ganese precipitated  by  phosphate  of  soda.  After  igni- 
tion the  precipitate  consists  of  2MnO,  P05. 

A  more  accurate,  but  still  not  absolute  separation, 
may  be  effected  by  neutralizing  the  solution  of  the 
chlorides  with  ammonia,  precipitating  the  metals  by 
sulphide  of  ammonium,  and  mixing  the  solution  with 
an  excess  of  very  dilute  hydrochloric  acid,  when  the 
sulphide  of  manganese  is  dissolved  with  great  facility, 
whilst  the  sulphides  of  nickel  or  cobalt  remain,  undis- 
solved. 

This  method  of  separation  is  perfectly  exact  if  the 
sulphides  be  used  which  were  formed  at  a  high  tempe- 
rature. The  oxides  are  precipitated  at  a  boiling  heat 
by  carbonate  or  hydrate  of  soda,  the  precipitate  ignited 
and  weighed,  and  then  heated  to  dull  redness  in  a  cur- 
rent of  sulphuretted  hydrogen,  in  a  porcelain  boat, 
placed  in  a  porcelain  tube.  When  cold,  the  porcelain 
boat  is  put  into  very  dilute  hydrochloric  acid,  which 
dissolves  the  manganese  only,  and  leaves  the  sulphide 
of  cobalt  or  nickel  behind.  The  conversion  of  the 
oxides  into  sulphides  may  likewise  be  effected  by 
fusing  them  in  a  porcelain  crucible  with  3  times  their 
weight  of  carbonate  of  soda  and  as  much  sulphur, 
after  which  the  mass  is  treated  with  dilute  hydrochloric 
acid. 

Or  nitrite  of  potassa  is  added  to  the  concentrated 
solution  of  the  three  metals,  which  precipitates  the 
cobalt  as  in  No.  65.  Acetate  of  soda  is  added  to  the 
filtered  solution,  and  chlorine  gas  passed  into  it,  when 
all  the  manganese  is  precipitated  as  superoxide.  The 
nickel  and  iron  remain  in  solution,  but  the  cobalt  is 
precipitated  with  the  manganese. 


METEORIC   IRON.  109 


69.  METEORIC  IRON. 

Iron  of  meteoric  origin  can  be  recognized  by  the 
following  peculiarities: — ' 

I.  Some  meteoric  iron  contains  olivine,  which  may 
be  detected  by  the  eye,  also  gold-colored  sulphuret  of 
iron. 

II.  In  certain  kinds,  especially  on  the  oxidized  sur- 
face, yellowish,  pliable  laminae  of  a  metallic  lustre  may 
be  observed ;  they  are  phosphide  of  nickel  and  iron 
(Schreibersite). 

III.  Some  kinds  are  passive,  i.  e.,  they  do  not  reduce 
copper  from  a  solution  of  neutral  sulphate  of  copper. 

IV.  If  a  freshly  filed,  ground  and  polished  surface 
be  immersed  for  five  or  ten  minutes  in  dilute  nitric 
acid,  peculiar,  mostly  crystalline  delineations   (Wid- 
mannstatten's  figures),  or    microscopic   parallel   lines 
or  bright  points,  make  their  appearance  in  most  kinds, 
thus  imparting  to  the  surface  a  peculiar  lustre  when 
viewed  in  a  certain  direction. 

V.  All  meteoric  iron,  when  dissolved  in  hydrochloric 
acid,  leaves  a  black,  pulverulent  residue,  whilst  in  most 
cases  a  trace  of  sulphuretted  hydrogen  is  developed, 
derived  from  an  admixture  of  sulphide  of  iron.     On 
examining  this  residue  (previously  washed  and  dried) 
under  a  magnifying  power  of  from  50  to  100,  in  most 
cases  crystalline  particles  of  metallic  lustre,  and  fre- 
quently also  well-defined  magnetic  prisms  of  metallic 
lustre,  are  observed,  consisting  of  phosphide  of  iron, 
phosphide  of    iron  and   nickel,  and   sometimes  also 
chrome-iron  and  graphite ;  in  addition  to  these  also 
transparent,  partly  colorless,  partly  colored  grains  of 
quartz,  olivine  and  other  minerals. 

VI.  Every  specimen  of  iron  of  undoubted  meteoric 
origin  contains  as  characteristic  constituents,  nickel, 
cobalt  and  phosphide  of  iron  and  nickel.    The  amount 
of  nickel  varies  between  2  and  20  per  cent. ;  the  cobalt 

10 


110  METEORIC  IRON. 

rarely  amounts  to  1  per  cent.,  and  the  insoluble  residue 
usually  amounts  to  3  per  cent. 

In  order  to  detect  the  nickel,  the  hydrochloric  solu- 
tion is  first  saturated  with  sulphuretted  hydrogen  in 
order  to  precipitate  traces  of  copper  and  tin,  which 
occasionally  occur;  the  protochloride  of  iron  is  then 
converted  into  sesquichloride  by  heating  the  solution 
nearly  to  boiling,  and  adding  small  quantities  of  chlo- 
rate of  potassa.  The  solution  is  then  mixed  with  an 
excess  of  ammonia,  when  all  the  sesquioxide  of  iron 
is  precipitated,  whilst  most  of  the  nickel  remains  dis- 
solved. When  the  amount  of  nickel  is  rather  large, 
the  filtered  liquor  is  more  or  less  blue.  Sulphide  of 
ammonium  precipitates  from  it  black  sulphide  of  nickel. 

Or  the  solution  is  neutralized  with  carbonate  of  soda, 
acetate  of  soda  added  and  boiled,  when  the  iron  with 
only  a  trace  of  nickel  is  precipitated,  the  nickel  and 
cobalt  remain  in  solution. 

In  order  to  detect  the  phosphoric  acid  contained  in 
the  sesquioxide  of  iron,  it  is  dried  and  ignited  with  an 
equal  weight  of  carbonate  of  potassa  and  soda,  and 
the  alkaline  phosphates  extracted  with  water.  The 
solution  is  then  supersaturated  with  acid  and  the  phos- 
phoric acid  precipitated  by  ammonia  and  sulphate  of 
magnesia. 

In  order  to  obtain  the  amount  of  phosphorus  con- 
tained in  the  black  residue  left  on  dissolving  meteoric 
iron  in  hydrochloric  acid,  it  is  finely  powdered,  mixed 
with  about  half  its  weight  of  nitrate  of  potassa  and 
then  with  an  equal  weight  of  carbonate  of  soda,  and 
ignited;  the  mass  is  then  extracted  with  water  and 
treated  as  above.  The  oxidized  residue  is  dissolved 
in  hydrochloric  acid  and  the  nickel  detected  as  above. 

In  quantitative  analyses  the  iron  is  separated  from 
the  nickel  and  cobalt,  either  by  succinate  of  ammonia, 
or  by  carbonate  of  baryta,  see  No.  25.  The  phosphoric 
acid  is  contained  in  both  precipitates.  Cobalt  and 


PLATINUM   METALS   AND   ORE.  Ill 

nickel  are  separated  by  cyanide  of  potassium  as  in 
No.  65. 


70.  THE  PLATINUM  METALS  AND  ORE. 

1.  PLATINUM. — Only  fusible  in  the  oxyhydrogen 
flame.     Density  when  fused  is  21.15.     Free  from  iri- 
dium  it  is  very  soft  and  malleable.     Soluble  in  aqua 
regia.      The  reddish-yellow  solution   gives  with  the 
salts  of  ammonium  and  potassium  a  crystalline  lemon 
yellow  precipitate,  NH4Cl  +  PtCl2  and  K  Cl-f  PtCl2. 
The  former  ignited  forms  a  gray  platinum  sponge,  and 
the  latter,  fused  with  common  salt,  crystallized  platinum. 

2.  PALLADIUM. — In  color,  lustre,  and  malleability, 
similar   to   platinum.     Difficultly   fusible,   but   more 
easily  than  platinum.     Density  11.8.     Heated  in  the 
air  it  is  colored  steel-gray,  and  in  the  flame  of  a  gas 
burner  becomes  rusty,  and  uniting  with  carbon  becomes 
brittle.     Soluble  in  cold  nitric  acid  without  disengage- 
ment of  gas.     Its  oxides  are  Pd2O,  PdO,  and  PdO2; 
they  are  black  and  reduced  without  a  flux. 

In  aqua  regia  it  gives  a  dark-brown  solution  of  per- 
chloride.  By  evaporation  it  becomes  a  dark-brown 
deliquescent  protochloride  Pd  Cl.  Iodide  of  potassium 
added  to  this  solution  forms  a  black  iodide  of  palladium, 
Pdl,  and  cyanide  of  mercury  a  yellowish-white  cyanide 
of  palladium  Pd  Cy. 

Ammonia  throws  down  a  flesh-red  crystalline  precipi- 
tate PdCl-hNH,,  forming  a  colorless  solution  if  an 
excess  of  ammonia  is  added.  Hydrochloric  acid  gives 
in  this  solution  a  lemon-yellow  crystalline  precipitate 
=  N.  PdH3-fCL,  which  leaves,  after  ignition,  the  gray 
metal.  If  one  ami  a  half  times  the  weight  of  the  metal 
of  chloride  of  potassium  be  added  to  the  solution  of 
palladium  in  aqua  regia,  and  evaporated  to  dryness,  a 
dark  red  crystalline  Pd  C12  +  KC1  is  formed,  insoluble 


112  PLATINUM   METALS  AND   ORE. 

in  alcohol,  scarcely  soluble  in  water,  a  means  by 
which  the  commercial  palladium,  iron,  and  copper  may 
be  separated. 

3.  IRIDIUM. — More  fusible  than  platinum.     Specific 
gravity  =  21.15.     In  its  isolated  form  it  is  unacted  on 
by  any  of  the  acids,  or  by  aqua  regia,  unless  alloyed 
with  platinum.     To  obtain  the  metal  in  the  separate 
state  the  powdered  alloy  is  intimately  mixed  with  an 
equal  weight  of  finely  powdered  chloride  of  sodium, 
and  the  mixture  heated  to  dull  redness  in  a  glass  tube 
through  which  a  current  of  dry  chlorine  is  passed  so 
long  as  it  is  absorbed.     The  resulting  dark-red  solu- 
tion of  double  chlorides  gives,  with  chlorides  of  am- 
monium and  potassium  in  a  hot  solution,  a  black  pre- 
cipitate of  NH4Cl  +  IrCl2,  or  KCl  +  IrCl2. 

If  the  metal  is  fused  with  nitrate  of  potassa  at  a 
strong  red  heat,  or  with  caustic  potassa  and  chlorate 
of  potassa,  it  is  converted  into  a  black  sesquioxide, 
mixed  with  potassa.  The  pulverized  metal  heated  to 
redness  oxidizes  in  the  air. 

4.  EHODIUM. — More  infusible  than  platinum.  After 
fusion  i4  has  a  specific  gravity   12.1.     Malleable.     If 
heated  to  redness  in  the  form  of  a  powder  in  the  air, 
it  oxidizes.     Insoluble  in  aqua  regia.     It  is  obtained 
as  a  soluble  double  salt  if  gently  ignited  in  a  stream 
of  chlorine,  if  pulverized  and  mixed  -with  chloride  of 
potassium,  or  chloride  of  sodium.     Both  double  salts 
(2KCl-f  K2C13)  are  easily  soluble  in  water,  also  the 
ammonium  salt.    They  are  insoluble  in  alcohol.   They 
form  dark-red  crystals.  t  Potassa  added  to  their  solu- 
tions, and  then  alcohol,  a  black  precipitate  of  rhodium 
is  formed.     The  pulverized  metal  fused  for  some  time 
with  a  large  excess  of  bisulphate  of  potassa,  and  until 
the  free  acid  is  driven  off,  forms  a  mass  soluble  in 
water.     If  chloride  of  potassium   and   hydrochloric 
acid  are  added  to  this  solution  and  evaporated,  it  be- 
comes rose-red. 


PLATINUM   METALS  AND   ORE.  113 

5.  RUTHENIUM. — Still  more  infusible  than  the  pre- 
ceding metals.    Sp.  gr.  =  11.3.  Brittle.    Pulverized  and 
heated  in  the  air  it  is  oxidized,  fused  with  hydrate  of 
potassa  and  saltpetre  or  chlorate  of  potassa,  it  forms 
ruthenite  of  potassa,  KO,  Ru  O3,  forming  with  water 
a  yellow  solution.    Neutralize  this  solution  with  nitric 
acid,  and  a  black  sesquioxide  is  thrown  down,  which 
is  easily  reduced  in  hydrogen  gas.     The  double  chlo- 
ride of  ruthenium  and  potassium,  KCl-f  Ru  Cl2is  easily 
soluble  in  water,  but  insoluble  in  alcohol.     The  red 
solution  is  not  precipitated  by  potassa  and  alcohol  in 
the  cold.     If  a  stream  of  chlorine  gas  is  conducted  into 
a  solution  of  ruthenite  of  potassa  ruthenic  acid  is  ob- 
tained, which  is  very  volatile,  of  a  yellow  color,  with 
a  strong  odor,  difficultly  soluble  in  water,  and  soon 
changing  to  black. 

6.  OSMIUM. — This  metal  alone  is  infusible  in  the 
strongest  oxy hydrogen  flame,  but  forms  a  bluish  me- 
tallic mass  with  sp.  gr.  =  21.4      It  volatilizes  at  the 
highest  temperature.     It   is  obtained   with  all    these 
properties,  if  sulphide  of  osmium  is  heated  in  a  strong 
coke  fire,  in  a  close  covered  graphite  crucible.     It  may 
be  prepared  in  the  crystalline  form  by  fusing  the  pul- 
verized osmium  with  six  or  eight  times  its  weight  of 
tin  in  a  graphite  crucible,  slowly  cooled,  and  the  tin 
dissolved  by  hydrochloric  acid.     Or  it  is  obtained  as 
a  bluish-black  powder  mass,  when  chloride  of  ammo- 
nium is  added  to  a  solution  of  osmiate  of  potassa  or 
ammonia,  evaporated  to  dry  ness,  and  the  mass  heated 
in  a  porcelain  retort  until  the  chloride  of  ammonium 
begins  to  volatilize ;  heating  this  with  water,  the  osmium 


remains. 

rn 


The  smallest  quantity  of  osmium  on  platinum  foil, 
held  in  the  flame  of  a  spirit  lamp,  becomes  brilliant, 
and  imparts  the  characteristic  odor  of  osmic  acid. 
Osmium,  heated  in  a  slow  stream  of  oxygen,-  forms 
osmic  acid.  It  is  also  formed  by  oxidizing  with  nitric 

10* 


114  PLATINUM   METALS   AND  ORE. 

acid.  It  is  very  volatile,  condenses  in  colorless  crys- 
tals, soluble  in  water,  with  a  very  pungent  odor  ex- 
tremely irritating  and  deleterious  to  the  eyes  and 
organs  of  respiration.  If  passed  in  the  vapor  form 
with  hydrogen  through  a  glass  tube  heated  to  redness, 
it  is  reduced  to  a  mirror  of  metallic  osmium.  The 
solution  heated  with  sulphurous  acid  becomes  violet. 
Potassa  precipitates  a  black  oxide  containing  potassa, 
and  easily  reduced  by  hydrogen.  The  solution  be- 
comes yellow  with  potassa  and  ammonia.  The  osmiate 
of  potassa  is  deep  yellow  crystalline.  Its  solution 
mixed  with  alcohol  precipitates  dark  red  crystalline 
osmite  of  potassa  KO,  Os  O,.  If  chloride  of  ammo- 
nium is  added  to  this  last  solution,  a  pale  yellow  crys- 
talline salt  of  ammonium  and  osmium  is  precipitated, 
which,  after  it  is  ignited  in  a  current  of  hydrogen, 
leaves  metallic  osmium. 

Both  the  chlorides  of  osmium  are  volatile.  The 
protochloride,  Os  Cl,  is  green,  the  bichloride,  Os  C12,  is 
dark  red.  The  double  chloride,  KCl-fOsCl2,  forms 
dark-brown  octahedrons,  giving  a  yellow  solution  in 
water. 

PLATINUM  ORE. 

(Platinum  with  small  quantities  of  Iridium,  Palla- 
dium, Rhodiurn;  Osmium,  Ruthenium,  Iron  and  Copper.) 

The  commercial  platinum  ore  usually  contains  grains 
of  sand,  of  osmium,  iridium,  and  often  of  gold.  In 
order  to  find  the  latter  the  mass  is  digested  in  rather 
dilute  aqua-regia,  until  scales  of  gold  are  no  longer 
visible.  The  solution  is  then  poured  off  from  the 
undissolved  platinum,  freed  from  nitric  acid  by  eva- 
poration, diluted,  oxalic  acid  added,  and  the  gold  pre- 
cipitated by  means  of  heat.  It  is  washed,  ignited,  and 
weighed. 

The  sand  is  determined  in  the  following  manner: 
A  small  quantity  of  borax  is  fused  in  a  clay  crucible, 


PLATINUM    METALS   AND   ORE.  115 

so  that  the  sides  may  be  covered  with  it,  then  eight 
grains  of  finely-divided  silver  are  placed  in  it,  and 
upon  this  two  grains  of  platinum  ore,  which  is  covered 
with  about  ten  grains  of  fused  borax.  The  mixture  is 
kept  in  a  state  of  fusion  for  some  time  at  a  temperature 
sufficient  to  melt  the  silver.  After  cooling  the  regulus 
is  freed  from  slag  and  weighed.  All  the  sand  is  taken 
up  by  the  slag  and  the  metal  by  the  silver. 

For  analysis,  ten  grammes  of  the  grains  of  real  plati- 
num are  picked  out  and  dissolved  at  a  boiling  heat,  in 
a  mixture  of  five  parts  of  fuming  hydrochloric  acid  and 
one  part  of  fuming  nitric  acid,  in  a  retort  connected 
with  a  receiver  which  is  to  be  kept  perfectly  cold. 

Fig.  14. 


The  acid  is  distilled  off'  until  the  contents  of  the  retort 
have  acquired  the  consistence  of  a  syrup.  The  mass 
becomes  solid  on  cooling;  it  is  then  dissolved  in  a 
small  quantity  of  water  and  the  clear  solution  carefully 
poured  off'from'the  residue.  The  acid  which  was  dis- 
tilled over  contains  osmic  acid,  and  is  colored  yellow 
by  a  portion  of  the  solution  which  was  mechanically 
carried  over ;  it  is  poured  back  on  the  residue  and 
again  distilled,  in  order  to  complete  the  solution. 

The  distillate  containing  osmic  acid  may  be  saturated 
with  ammonia  and  the  osmium  separated  as  in  No.  71. 
Or  it  is  nearly  saturated  with  hydrate  of  lime,  mixed 
with  an  alkaline  formate  and  boiled,  when  the  osmium 
is  reduced  as  a  bluish-black  powder,  which  is  ignited 


116  PLATINUM   METALS  AND  ORE. 

in  a  current  of  hydrogen  when  the  osmium  is  obtained 
in  the  metallic  state,  and  weighed. 

The  platinum-solution  is  filtered  off  from  the  insolu- 
ble residue,  which  is  collected  on  a  weighed  filter  and 
washed.  It  consists  of  irid-osmine,  and  is  farther 
treated  as  in  No.  71. 

The  solution  is  evaporated  to  dryness,  the  mass 
heated  to  150°  in  order  to  convert  the  chloride  of 
iridium  into  sesquichloride.  It  is  then  dissolved  in  a 
little  water  containing  a  few  drops  of  hydrochloric 
acid,  mixed  with  a  concentrated  solution  of  chloride 
of  ammonium,  the  precipitate  filtered  oft^  washed  with 
a  solution  of  chloride  of  ammonium,  and  then  with 
alcohol.  The  double  salt,  when  dried,  is  ignited  with 
the  filter,  a  few  crystals  of  oxalic  acid  being  placed  in 
the  crucible  to  facilitate  the  reduction. 

The  platinum  and  iridium  thus  obtained  are  weighed, 
again  dissolved  in  dilute  aqua-regia,  and  the  iridium 
which  remains  filtered  off,  washed,  and  ignited  in  a 
stream  of  hydrogen. 

The  filtrate  from  which  the  double  chloride  of  plati- 
num and  ammonium  was  precipitated,  is  concentrated 
by  evaporation,  boiled  with  concentrated  nitric  acid 
to  decompose  the  chloride  of  ammonium,  saturated 
with  chlorine  gas  until  the  solution  of  chloride  of 
iridium  has  a  brownish-red  color.  It  is  then  com- 
pletely evaporated  to  dryness  on  a  water-bath,  the  mass 
pulverized  and  treated  with  alcohol"  of  80  per  cent., 
filtered  and  washed  with  alcohol  until  it  flows  through 
colorless.  This  solution  contains  all  the  iron  and  cop- 
per which  are  determined  by  themselves. 

The  insoluble  salt,  which  contains  besides  the  os- 
mium and  ruthenium,  all  the  platinum  metals,  is  washed 
with  a  weak  solution  of  chloride  of  ammonium  until 
the  reddish  solution  becomes  colorless.  This  solution 
contains  all  the  rhodium  and  palladium.  It  is  evapo- 
rated to  dryness,  ignited  in  a  covered  platinum  crucible, 


PLATINUM   METALS   AND   ORE.  117 

and  the  metal  reduced  in  a  current  of  hydrogen.  The 
weighed  metal  is  digested  with  dilute  aqua-regia,  the 
solution  which  contains  all  the  palladium  with  a  little 
rhodium,  evaporated  to  dry  ness,  a  few  drops  of  caustic 
potassa  added,  and  the  palladium  precipitated  by  a 
saturated  solution  of  cyanide  of  mercury.  The  pre- 
cipitate is  washed,  dried,  ignited  in  a  stream  of  hydro- 
gen, and  weighed  as  metallic  palladium. 

The  solution  which  contains  the  rhodium,  is  made 
slightly  alkaline  with  soda,  evaporated  to  dryness,  the 
mass  ignited  to  drive  off  the  mercury  and  treated  with 
water.  The  oxide  of  rhodium  which  remains  undis- 
solved  is  added  to  that  left  from  the  solution  of  the 
palladium  and  ignited  in  hydrogen  gas. 

The  portion  of  the  salt  which  contained  the  platinum 
and  iridium,  and  which  remained  insoluble  in  the 
chloride  of  ammonium,  is  digested  with  a  weak  solu- 
tion of  cyanide  of  potassium  added  gradually,  until  the 
color  has  changed  to  a  light  yellowish-brown,  and  is 
converted  into  a  double  salt  of  chloroplatinate  of  po- 
tassium and  ammonium,  which  is  washed  with  a  so- 
lution of  chloride  of  ammonium.  By  dissolving  in 
boiling  water  it  is  obtained  in  dark  yellow  octahedral 
crystals.  It  is  ignited,  placing  in  the  crucible  near 
the  close  of  the  operation  some  crystals  of  oxalic  acid, 
and  the  chloride  of  potassium  extracted  with  water. 

The  filtrate  which  contains  the  iridium  is  evaporated 
to  dryness,  ignited  to  drive  off'  the  chloride  of  ammo- 
nium, and  finally  fused  with  some  nitrate  of  potassa. 
The  sesquioxide  of  iridium  containing  the  alkali 
which  remained  insoluble  when  treated  with  water, 
is  well  washed,  reduced  by  hydrogen,  and  the  alkali 
extracted  with  water. 


118          IRIDOSMINE   AND   PLATINUM   RESIDUES. 


71.  IRIDOSMINE  AND  PLATINUM  RESIDUES. 

I.  Iridosmine  occurs  in  small  scales  and  mostly  steel 
colored,  extremely  hard,  and  of  sp.  gr.  18  to  20.  It  is 
contained  entirely  in  the  residue  in  the  solution  of 
platinum,  mostly  in  the  form  of  very  fine  plates.  Its 
composition  is  variable.  Besides  the  two  principal 
metals,  it  contains  more  or  less  rhodium  and  ruthenium, 
with  small  quantities  of  platinum,  copper,  and  iron. 
It  is  insoluble  in  aqua  regia. 

The  osmium  may  be  extracted  for  the  most  part 
from  the  variety  made  up  of  very  fine  grains*  or  pow- 
der by  roasting.  The  ore  is  placed  in  a  porcelain  tube 
heated  to  redness,  and  a  slow  stream  of  air  or  oxygen 
gas  passed  over  it.  The  end  of  the  porcelain  tube 
passes  into  a  well-cooled  receiver,  from  which  the 
osmic  acid  is  conducted  into  a  solution  of  caustic 
potassa. 

The  fine  pulverulent  variety  is  mixed  with  an  equal 
weight  of  common  salt,  and  a  stream  of  moist  chlorine 
passed  over  it,  in  a  porcelain  tube  heated  to  redness, 
and  then  treated  as  in  No.  71,  II. 

In  order  to  pulverize  the  coarse  grained  kind,  it  is 
fused  with  six  times  its  weight  of  pure  zinc,  in  a  cru- 
cible placed  in  a  second  crucible  and  surrounded  by 
charcoal  powder,  well  covered  and  heated  to  redness 
for  half  an  hour  and  to  a  white  heat  for  two  hours 
until  all  the  zinc  is  volatilized.  The  iridosmine  is  left 
in  the  form  of  a  glistening  friable  sponge. 

From  this  sponge  the  osmium  may  be  volatilized  by 

*  A  species  in  form  of  a  very  heavy  gray  salt,  and  probably  ob- 
tained from  the  dressing  of  the  gold  sands  of  California,  contains 
gtill  more  gold  and  much  chloride  of  silver,  which  must  be  ex- 
tracted by  concentrated  ammonia  before  it  is  made  use  of. 

Species  containing  sand  must  be  purified  by  fusing  with  carbo- 
nate of  soda  and  treating  the  mass  with  water. 


IRIDOSM1NE   AND   PLATINUM    RESIDUES.          119 

heating  in  the  oxyhydrogen  flame,  the  indium  contain- 
ing ruthenium  and  rhodium  will  be  fused. 

The  pulverulent  iridosmine  is  easily  separated  by 
fusing  in  a  silver  crucible  with  caustic  potassa  and 
chlorate  of  potassa.  It  is  heated  carefully  in  the  be- 
ginning on  account  of  the  frothing,  but  finally  to  red- 
ness. The  mass  is  treated  with  water^  until  dissolved, 
and  then  left  in  a  high  closed  vessel  until  it  has  settled 
clear.  The  deep  yellow  solution  of  osmiate  and  ru- 
theniate  of  potassa  are  drawn  off  clear  by  means  of  a 
syphon,  and  the  black  residue,  consisting  of  oxides  of 
rhodium  and  iridium  treated  again  in  the  same  manner 
with  M^ater.  From  the  yellow  solution  ruthenium  is 
precipitated  as  a  black  oxide  by  carefully  neutralizing 
with  nitric  acid.  It  is  reduced  by  means  of  hydrogen. 

The  solution  containing  osmium  is  made  alkaline 
with  potassa,  alcohol  added  and  heated,  whereby  the 
osmium  is  precipitated  as  a  black  oxide  containing 
potassa.  It  is  ignited  in  hydrogen  and  the  potassa 
removed  by  water. 

The  oxide  of  iridium  is  reduced  by  heating  in  hydro- 
gen, washed,  intimately  mixed  with  an  equal  weight 
of  fused  chloride  of  sodium,  and  gently  ignited  in  a 
current  of  chlorine,  until  the  gas  passes  off  unabsorbed 
in  excess.  The  resulting  double  chloride  is  dissolved  in 
water,  the  solution  concentrated  and  mixed  with  an  ex- 
cess of  a  hot  saturated  solution  of  chloride  of  potassium, 
when  the  iridium  is  precipitated  as  a  black  crystalline 
double  chloride.  It  is  then  washed  with  a  saturated 
solution  of  chloride  of  potassium.  (It  may  also  con- 
tain some  of  the  ruthenium  salt  precipitated  at  the 
same  time.  In  order  to  extract  this  the  metal  is  fused 
with  caustic  and  chlorate  of  potassa.) 

The  solution  which  contains  the  rhodium  and  the 
ruthenium  is  concentrated,  formate  of  soda  added  and 
boiled,  when  all  the  rhodium  is  precipitated.  The 


120          IRIDOSMINE   AND   PLATINUM   RESIDUES. 

filtrate  is  acidified  with  hydrochloric  acid,  and  the 
ruthenium  precipitated  by  pure  zinc. 

The  following  method  may  be  used  for  the  analysis 
of  iridosmine.  Two  .grains  of  the  substance,  in  a  fine 
powder,  are  intimately  mixed  with  six  grains  of  per- 
oxide of  barium  and  two  of  nitrate  of  baryta*  in  a  close 
covered  silver  crucible,  and  heated  to  redness  for  about 
two  hours.  The  unfused  mass  is  taken  from  the  cru- 
cible, treated  with  water,  and  hydrochloric  acid  added 
until  it  dissolves.  It  is  then  mixed  with  nitric  acid, 
and  gently  boiled  until  the  smell  of  osmic  acid  is  no 
longer  perceptible/)*  It  is  then  carefully  evaporated 
to  dryness,  dissolved  in  hot  water,  the  liquid  decanted 
from  the  iridosmine,  which  has  been  somewhat  acted 
upon. 

The  baryta  in  the  solution  is  precipitated  by  sulphu- 
ric acid,  and  after  it  has  completely  settled,  and  the 
liquid  become  clear,  it  is  filtered. 

About  eight  grammes  of  pure  chloride  of  ammonium 
are  mixed  with  the  yellowish-red  solution,  evaporated 
to  dryness,  and  a  small  quantity  of  chloride  of  ammo- 
nium mixed  with  alcohol  added  to  the  mass,  the  salt 
of  iridium  filtered  off,  washed  as  at  first,  with  a  solu- 
tion of  chloride  of  ammonium,  then  with  weak  and 
afterwards  strong  alcohol.  The  dried  salt,  together 
with  the  filter,  is  placed  in  a  covered  platinum  cru- 
cible and  very  gradually  and  carefully  heated  to  red- 
ness, the  filter  then  thoroughly  burned,  and  the  metal 
reduced  by  conducting  hydrogen  gas  into  the  crucible 
or  holding  a  piece  of  carbonate  of  ammonia  in  it 
while  heated. 

*  These  two  products  should  be  very  accurately  weighed,  in 
order  to  determine  beforehand  the  exact  quantity  of  sulphurous 
acid  necessary  to  precipitate  the  baryta.  The  nitrate  of  baryta 
must  be  decrepitated. 

f  The  osmic  acid  may  be  driven  off  in  a  retort  and  absorbed  by 
a  solution  of  ammonia. 


PLATINUM   KESIDUES.  121 

The  ruthenium  is  combined  with  the  iridium.  They 
are  separated,  as  already  stated,  by  fusing  with  caustic 
and  chlorate  of  potassa. 

The  rhodium  is  contained  in  the  remaining  solution 
of  chloride  of  ammonium.  It  is  heated  with  a  large 
excess  of  nitric  acid,  evaporated  to  a  small  quantity, 
placed  in  a  weighed  porcelain  crucible,  evaporated  to 
dryness,  and  the  salt,  heated  to  redness,  is  reduced  by 
conducting  a  stream  of  hydrogen  upon  it. 

The  iron,  copper,  baryta,  and  alumina  (the  last  from 
the  peroxide  of  barium)  are  separated  by  alternate 
treatment  with  hydrochloric  and  nitric  acids. 

The  solution  is  neutralized  with  carbonate  of  soda, 
and  the  palladium  precipitated  by  a  solution  of  cyanide 
of  mercury.  The  yellowish-white  cyanide  of  palla- 
dium having  settled,  it  is  filtered  off,  washed,  and  ig- 
nited, when  metallic  palladium  is  left  behind. 

The  filtered  solution  is  boiled  with  hydrochloric  acid 
until  it  has  assumed  a  red  tint,  and  the  hydrated  oxide 
of  rhodium  is  then  precipitated  by  caustic  potassa.  By 
ignition  in  hydrogen  it  is  reduced  to  the  metallic  state. 

From  the  solution  which  contains  the  rhodium  and 
palladium  both  metals  may  also  be  precipitated  by 
pure  zinc,  with  the  addition  of  hydrochloric  acid,  the 
precipitate  washed,  and  the  palladium  extracted  by 
nitric  acid,  in  which  the  rhodium  is  insoluble. 

If  the  rhodium  be  not  reduced  by  formic  acid,  the 
solution  obtained  with  bisulphate  of  potassa  might  also 
be  mixed  with  formate  of  soda  and  boiled,  when  pal- 
ladium is  separated  in  the  metallic  state.  If  both  be 
reduced,  the  palladium  could  be  extracted  from  the 
mixture  by  means  of  nitric  acid. 

II.  PLATINUM-RESIDUES. 

There  are  two  kinds.  The  kind  A  is  that  which 
remains  insoluble  when  large  quantities  of  platinum 


122  PLATINUM    RESIDUES. 

ore  are  dissolved ;  the  kind  B  is  obtained  as  a  precipi- 
tate by  iron  in  the  last  mother  liquor  from  the  prepa- 
ration of  platinum. 

A.  This  residue  is  formed  of  grains  and  scales  of  irid- 
osmine,  together  with  pulverulent  iridium  with  very 
small  quantities  of  palladium,  rhodium,  and  platinum, 
mixed  with  titanic  iron,  chromic  iron,  and  sand.  These 
last  three  sometimes  amount  to  70  or  80  per  cent.,  and 
also  contain  traces  of  chlorides  of  silver  and  gold.  To 
extract  the  precious  metals  a  variety  of  methods  are 
employed. 

The  coarse  granular  kind  is  broken  and  ground  as 
finely  as  possible,  to  reduce  the  grains  of  the  iron  ores 
to  powder.  It  is  then  levigated  with  water,  when  most 
of  the  irid-osmine  is  separated  in  larger  grains  and 
scales. 

1.  The  levigated  black  powder  is  intimately  mixed 
with  about  its  own  bulk  of  decrepitated  and  finely- 
powdered  chloride  of  sodium,  the  mixture  introduced 
into  a  porcelain  or  glass  tube,  and  gently  ignited  in  a 
slow  current  of  undried  chlorine-gas  until  the  latter 
commences  to  pass  through  the  tube  unabsorbed. 

The  other  end  of  the  tube  dips  into  a  well-cooled, 
tubulated  receiver  from  the  tubulure  of  which  a  gas- 
tube  conducts  the  excess  of  chlorine  into  milk  of  lime. 

By  this  process  sodio-chlorides  of  iridium  and  of 
osmium  are  formed.  The  greater  portion  of  the  latter 
is  decomposed  by  the  moisture  of  the  chlorine-gas,  and 
the  osmic  acid  formed  from  it  partly  sublimes  in  the 
receiver,  and  is  partly  conducted  into  the  hydrate  of 
lime. 

The  residue  in  the  tube,  when  cold,  is  treated  with 
water,  and  is  at  last  washed  with  hot  water. 

The  dark  yellowish-red  solution  of  iridium  filtered 
off  from  the  iron  ore  is  mixed  with  concentrated  nitric 
acid  and  distilled,  when  osmic  acid  passes  over,  dis- 
solved in  water.  The  liquid  thus  very  much  concen- 


PLATINUM    RESIDUES.  123 

trated,  is,  whilst  still  hot,  mixed  with  a  saturated  solu- 
tion of  chloride  of  potassium,  when,  on  cooling,  a  great 
portion  of  the  iridium  separates  in  the  form  of  crystal- 
line black  chloride  of  iridium  and  potassium,  which  is 
filtered  off  and  several  times  washed  with  solution  of 
chloride  of  potassium. 

The  remaining  solution  is  mixed  with  crystallized 
carbonate  of  soda  in  excess,  evaporated  to  dryness,  the 
mass  gently  ignited  in  a  crucible,  and  when  cold 
washed  with  hot  water,  which  usually  acquires  a  yellow 
color,  owing  to  the  presence  of  an  alkaline  chromate. 

The  black  powder  which  is  left  undissolved,  consists 
of  a  compound  of  sesquioxide  of  iridium  with  soda, 
contaminated  with  sesquioxide  of  iron.  It  is  reduced 
by  being  gently  heated  in  a  current  of  hydrogen. 
Water  then  extracts  caustic  soda,  and  the  iron  is 
removed  by  digestion  with  hydrochloric  acid.  On 
digesting  it,  after  this  treatment,  with  some  very  dilute 
nitro-hydrochloric  acid,  a  small  amount  of  platinum  is 
usually  extracted,  which  may  then  be  precipitated 
with  chloride  of  ammonium. 

The  iridium  in  the  first  solution  maybe  precipitated 
by  chloride  of  ammonium  instead  of  chloride  of  potas- 
sium. When  the  black  perchloride  of  iridium  and  am- 
monium is  washed  with  a  solution  of  chloride  of  ammo- 
nium, and  then  digested  with  a  solution  of  cyanide  of 
potassium,  it  is  completely  dissolved  if  it  is  free  from 
platinum,  as  a  protochloride.  If  it  contains  platinum, 
there  remains  undissolved  a  light  brown  residue,  soluble 
in  hot  water,  which  crystallizes  in  dark  yellow  octa- 
hedrons. This  salt  has  the  composition  expressed  by 
the  formula  (NH4,  K)  Cl  +  Pt  C12. 

Or  the  chloride  of  iridium  and  ammonium  or  potas- 
sium is  melted  in  a  porcelain  crucible  with  one  and  a 
half  times  its  weight  of  cyanide  of  potassium,  the  mass 
dissolved  in  a  little  water,  filtered,  an  excess  of  acetic 
acid  added  to  decompose  the  free  cyanide  of  potassium, 


124  PLATINUM   RESIDUES. 

heated  to  boiling  (whereby  red  sesqui-cyanide  of  rho- 
dium may  be  precipitated),  and  the  platinum  precipi- 
tated by  sulphate  of  copper.  The  violet  precipitate, 
a  mixture  of  double  cyanide  of  platinum  and  copper, 
and  of  double  cyanide  of  iridiurn  and  copper,  is  washed 
with  hot  water  and  then  boiled  with  caustic  baryta. 
The  cyanides  of  platinum  and  of  barium,  very  solu- 
ble in  hot  water,  but  scarcely  soluble  in  cold,  may  be 
easily  separated  from  the  colorless  and  more  soluble 
salts  of  iridium  by  crystallization. 

The  iridium  reduced  by  hydrogen  and  freed  from 
iron,  may  contain  ruthenium  and  rhodium.  To  extract 
the  first  it  is  fused  with  caustic  potassa  and  chlorate  of 
potassa,  and  afterwards  to  extract  the  latter  with  bisul- 
phate  of  potassa.  (See  No.  70.) 

The  sesquioxide  of  iridium  from  the  metal  obtained 
by  the  calcination  of  the  double  chloride  of  ammonium, 
may  be  brought  to  a  coherent  mass  by  a  strong  pres- 
sure, and  heating  to  a  white  heat;  it  is  then  placed  in 
a  burnt  lime  crucible,  and  fused  by  an  oxyhydrogen 
jet. 

The  metal  may  be  extracted  from  the  osmic  acid  by 
the  process  given  in  No.  70. 

A  single  treatment  of  a  platinum  residue  is  not 
generally  sufficient,  but  it  must  be  repeated  several 
times. 

2.  The  minerals  mixed  with  the  platinum  metals 
are  separated  by  fusing  the  residues  with  a  flux,  and 
lead,  which  dissolves  the  noble  metals.  The  platinum 
residue  is  mixed  with  (not  more  than  300  or  400 
grms.  at  a  time)  an  equal  weight  of  granulated  lead, 
and  one  and  a  half  times  its  weight  of  litharge,  and 
melted  in  a  crucible  with  a  thick  bottom,  until  com- 
pletely fused.  It  is  stirred  from  time  to  time  with  an 
earthenware  rod  to  unite  the  grains  of  metal,  the  cru- 
cible is  taken  from  the  fire  (before  the  oxide  of  lead 
has  penetrated  it),  gently  struck  a  few  times  and  left 


PLATINUM   RESIDUES.  125 

to  cool.  The  lead  button  formed  is  freed  from  slag, 
and  dissolved  in  moderately  strong  hot  nitric  acid. 
The  platinum  metals  remain  in  the  state  of  a  black 
powder,  and  as  grains  and  scales.  They  are  then 
treated  as  above. 

In  the  lead  solution  which  may  contain  palladium, 
the  lead  is  precipitated  by  sulphuric  acid.  It  is  then 
evaporated  to  dryness,  the  mass  again  dissolved  in  a 
little  water,  and  the  palladium  precipitated  by  cyanide 
of  mercury. 

Another  good  flux  for  this  operation,  which  attacks 
the  crucible  less,  is  a  mixture  of  fluorspar  and  an- 
hydrous gypsum  of  equal  equivalent  weights  (I  pt. 
CaF,  and  1.7  pt.  CaO,  So3),  1  pt.  of  platinum  residue, 
1  pt.  granulated  lead,  and  2  pts.  of  flux. 

3.  The  platinum  residue  is  fused  with  an  equal 
weight  of  caustic  potassa  and  twice  its  weight  of  nitrate 
of  potassa,  in  an  iron  crucible,  finally  heated  to  redness 
with  frequent  stirring.  The  mass  is  poured  out,  coarsely 
powdered,  hot  water  added,  mixed  with  one-tenth  al- 
cohol, and  boiled  until  completely  decomposed.  By 
this  means  the  esmate  of  potassa  is  changed  to  osmite, 
the  ruthenite  of  potassa  completely  decomposed  with 
separation  of  black  oxide  of  ruthenium.  The  washed 
black  residue  is  mixed  with  the  liquid  from  the  coarse 
heavy  grains  and  scales  not  acted  upon,  which  are 
fused  for  the  second  and  third  time  with  potassa  and 
nitrate  of  potassa,  until  at  last  only  oxide  of  iron  re- 
mains. 

The  clear  alkaline  solution  from  the  osmate  of 
potassa  is  drained  off  by  means  of  a  syphon  from  the 
black  residue,  and  this  again  washed  with  hot  water 
containing  alcohol.  The  black  mass,  which  still  con- 
tains much  osmium,  is  placed  in  a  tubulated  retort, 
with  a  funnel  tube,  and  to  this  a  receiver  is  placed, 
which,  with  large  quantities,  is  united  to  some  Woulfe's 
bottles  bv  large  tubes  filled  with  a  mixture  of  alcohol 


126  THALLIUM. 

and  solution  of  caustic  potassa.  Concentrated  hydro- 
chloric acid  is  gradually  poured  through  the  funnel- 
tube,  and,  after  the  first  reaction  has  ceased,  the  distil- 
lation is  continued  with  aid  of  heat,  as  long  as  osmic 
acid  passes  over.  It  is  then,  with  very  careful  man- 
agement on  account  of  the  injurious  action  of  the  vapor 
upon  the  respiratory  organs  and  eyes,  dissolved  in  the 
solution  of  potassa,  the  fluid  added  to  the  alkaline  so- 
lution obtained  after  the  fusion  of  the  ore  with  caustic 
potassa  and  nitrate  of  potassa,  and  the  whole  evapo- 
rated until  crystals  of  red  osmate  of  potassa  are 
formed.  The  rest  of  the  osmium  can  be  precipitated 
in  the  mother  liquor  by  chloride  of  ammonium.  (See 
No.  70.) 

The  dark  brownish-red  solution  in  the  retort  is  eva- 
porated to  dryness,  the  mass  again  dissolved  in  hot 
water,  and  the  solution  mixed  with  a  hot  saturated 
solution  of  chloride  of  potassium  in  large  excess.  The 
indium,  platinum,  rhodium,  and  ruthenium  are  pre- 
cipitated as  double  salts  insoluble  in  the  solution,  and 
washed  with  a  saturated  solution  of  chloride  of  potas- 
sium. The  iron  and  palladium  remain  undissolved. 

Kesidue,  B.  It  is  brownish-black,  earthy,  and  rich 
in  rhodium,  but  contains  much  silica,  alumina,  gypsum, 
iron,  &c.  To  separate  these  impurities  it  may  be  fused 
with  lead  and  litharge,  or  with  several  times  its  weight 
of  carbonate  of  soda.  In  the  latter  case  the  mass  is 
first  washed  with  hot  water,  digested  with  hydrochlo- 
ric acid,  and  then  treated  as  the  other  residue. 


72.  THALLIUM. 

I.  This  element  was  discovered  by  Crookes  in  18B1, 
in  a  seleniferous  deposit  from  a  sulphuric  acid  manu- 
factory in  the  Hartz.  The  name  is  derived  from 


THALLIUM.  127 

"  green,"  because  its  existence  was  first  recognized  by 
an  intense  green  line,  appearing  in  the  spectrum  of  a 
flame  in  which  thallium  was  volatilized.  It  was  at 
first  suspected  to  be  a  metalloid,  but  further  examina- 
tion proved  it  to  be  a  true  metal.  It  was  first  obtained 
in  a  distinct  metallic  form  by  Crookes  towards  the 
end  of  the  year  1861,  and  about  the  same  time  by 
Lamy,  who  prepared  it  from  a  deposit  of  the  lead 
chamber  of  M.  Kuhlmann,  of  Lille. 

Thallium  is  very  widely  diffused  as  a  constituent  of 
iron  and  copper  pyrites,  though  it  never  constitutes 
more  than  the  4000th  part  of  the  bulk  of  the  ores.  It 
also  occurs  in  some  specimens  of  blende  and  calami ne, 
sulphide  of  cadmium,  native  sulphur;  in  bismuth,  mer- 
cury, and  antimony  ores,  and  in  the  manufactured  pro- 
ducts from  these.  It  is  also  found  in  some  specimens  of 
lepidolite  and  mica,  and  in  certain  brines,  as  those  of 
Nauheim,  in  which  it  was  found  associated  with  chlo- 
rides of  caseium  and  rubidium. 

II.  The  easiest  mode  of  extracting  the  metal  consists 
in  treating  the  thalliferous  dust  deposited  in  the  flues 
of  the  sulphuric  acid  works  before  they  enter  the 
chamber,  with  an  equal  weight  of  boiling  water,  draw- 
ing off  the  clear  liquor,  and  treating  the  undissolved 
portion  again  in  like  manner.  The  clear  liquids  are 
next  mixed  with  a  large  excess  of  strong  hydrochloric 
acid,  by  which  a  precipitate  of  impure  chloride  of 
thallium  is  obtained.  This  is  then  washed,  pressed, 
and  decomposed  by  treating  it  with  an  equal  weight 
of  concentrated  sulphuric  acid.  The  acid  sulphate  of 
thallium  thus  obtained  is  dissolved  in  about  20  parts 
of  water,  filtered,  ajad  again  precipitated  as  tolerably 
pure  chloride  by  the  addition  of  hydrochloric  acid  in 
excess.  The  precipitate  is  washed,  pressed,  and  again 
converted  into  sulphate  by  adding  about  two-thirds 
of  its  weight  of  oil  of  vitriol  and  heating  until  all  the 
hydrochloric  acid  is  expelled ;  a  dense  liquid  is  thus 


128  THALLIUM. 

obtained,  which  as  it  cools  solidifies  to  a  white  mass 
of  acid  sulphate  of  thallium.  This  is  dissolved  in  about 
ten  times  its  weight  of  hot  water,  filtered,  and  allowed 
to  crystallize.  It  may  be  purified  by  recrystallization, 
and  if  the  solution  be  decomposed  by  metallic  zinc, 
or  by  the  voltaic  battery,  pure  thallium  is  abundantly 
and  easily  obtained.  It  may  be  melted  in  an  iron 
crucible  heated  over  a  gas  flame,  maintaining  a  current 
of  coal  gas  through  the  crucible  to  prevent  oxidation. 

Thallium  and  its  compounds  are  most  easily  and 
certainly  detected  by  spectral  analysis.  The  spectrum 
is  characterized  by  a  single  bright  green  line  coinci- 
dent with  Ba,  £.  It  is,  however,  usually  perceptible 
for  but  a  moment,  and  its  intensity  and  duration  do 
not  safely  indicate  the  amount  of  thallium  present  in 
sulphides,  flue-dust,  &c. 

To  find  thallium  in  native  sulphur  the  latter  is 
mostly  dissolved  by  sulphide  of  carbon,  and  the  residue 
examined  as  above.  In  pyrites,  flue  dust,  and  sul- 
phuric-acid chamber  sediment,  it  may  be  usually  de- 
tected at  once  by  the  spectroscope.  The  sublimate 
obtained  by  strongly  heating  finely  pulverized  sul- 
phides in  a  closed  glass  tube  often  gives  the  reaction 
when  none  can  be  obtained  from  the  substance  itself. 

III.  Thallium  is  a  heavy  metal  resembling  lead  in 
its  physical  properties.  Its  specific  gravity  is  11.81 
to  11.91.  The  freshly-cut  surface  of  the  metal  has  a 
bluish-white  lustre  resembling  zinc,  which  quickly  tar- 
nishes in  the  air,  a  thin  film  of  oxide  being  formed. 
It  is  soft,  malleable,  and  may  be  pressed  into  wire, 
though  its  tenacity  is  weak.  It  produces  a  streak  on 
paper  like  graphite.  It  melts  if  Cheated  in  oxygen, 
and  burns  with  an  intense  green  flame.  It  combines 
directly  with  chlorine,  bromine,  iodine,  sulphur,  and 
phosphorus.  It  is  very  soluble  in  nitric  and  sulphuric 
acids,  but  the  action  of  hydrochloric  is  slow  even  when 


THALLIUM.  129 

hot,  owing  to  the  insolubility  of  the  chloride.  It  forms 
alloys  with  most  of  the  metals. 

Thallium  forms  two  oxides — a  protoxide  and  a 
sesquioxide.  Both  the  oxides  dissolve  readily  in  acids, 
forming  definite  crystallizable  salts,  soluble  in  water ; 
there  are  also  a  few  insoluble  salts  obtained  by  double 
decomposition. 

IV.  Detection. 

1.  In  the  dry  way. — The  most  characteristic  property 
of  thallium  is  the  intense  green  color  which  the  metal 
or  any  of  its  compounds  communicates  to  a  colorless 
flame.    This  color  examined  in  the  spectroscope  appears 
as  one  intensely  brilliant  and  sharp  green  line.     The 
spectral  reaction  is  very  delicate,  the  five-millionth  part 
of  a  grain  of  the  sulphate  being  sufficient  to  produce 
it.     Thallium  salts  when  ignited  generally  fuse  below 
redness,  and  then  volatilize;  some  of  them,  however, 
as  the  sulphate  and  phosphate,  will  stand  a  bright  red 
heat  without  change :  the  chlorides,  on  the  other  hand, 
distil  over  with  vapor  of  water.     On  charcoal  before 
the  blowpipe  they  volatilize,  giving  an  intense  green 
color  to  the  flame. 

2.  In  solution. — Salts  of  the  protoxide  are  for  the 
most  part  colorless,  unless  the  acid  itself  is  colored. 
They  are  mostly  soluble  in  water,  neutral  to  test  paper, 
and  have  a  slight  metallic  taste.     Their  aqueous  solu- 
tion is  rapidly  precipitated  in  metallic  crystals  by  zinc, 
and  slowly  by  iron.     Hydrosulphuric  acid  added  to  a 
solution  of  a  protoxide  salt  containing  a  weak  acid, 
such  as  carbonic  or  acetic,  separates  the  whole  of  the 
metal  in  the  form  of  a  deep  brown  sulphide;  from 
solutions  of  the  peroxide  salts  of  the  stronger  acids, 
such  as  the  sulphate  or  nitrate,  hydrosulphuric  acid 
precipitates  nothing  if  the  acid  is  in  excess,  and  only 
a  small  portion  of  the  metal  if  the  solution  is  neutral. 
Sulphide  of  ammonium  precipitates  peroxide  salt  com- 
pletely, the  precipitated  sulphide  being  insoluble  in 


ISO  THALLIUM. 

sulphide  of  ammonium,  in  caustic  alkalies,  their  car- 
bonates and  cyanides,  and  only  slightly  soluble  in 
acetic  acid.  Hydrochloric  acid  and  soluble  chlorides 
precipitate  a  difficultly  soluble  white  chloride ;  hydro- 
bromic  acid  and  bromides  precipitate  a  white  nearly 
insoluble  bromide ;  and  hydriodic  acid  and  iodides  an 
insoluble  yellow  iodide.  Alkalies  and  alkaline  car- 
bonates produce  no  change  in  salts  of  the  protoxide  ; 
phosphate  of  soda  gives  a  white  precipitate,  nearly  in- 
soluble in  ammonia,  easily  soluble  in  acids.  Chromate 
of  potassa  gives  a  yellow  precipitate  of  chromate  of  the 
protoxide.  Bichloride  of  platinum  precipitates  a  very 
pale  yellow  insoluble  double  salt. 

From  these  reactions  it  appears  that  in  examining 
a  mixed  metallic  solution,  according  to  the  ordinary 
method  of  qualitative  analysis  thallium  will  be  found 
in  the  precipitate  thrown  down  by  sulphide  of  ammo- 
nium, together  with  iron,  nickel,  manganese,  &c.  From 
these  metals  it  may  be  easily  separated  by  precipitat- 
ing with  iodide  of  potassium,  or  bichloride  of  platinum, 
or  by  reduction  to  the  metallic  state  by  zinc.  Iodide 
of  potassium  is — next  to  the  spectral  reactions — the 
most  delicate  of  all  tests  for  thallium. 

3.  Salts  of  the  sesquioxide  are  easily  distinguished 
from  those  of  protoxide  by  their  behavior  with  alkalies, 
and  with  soluble  chlorides  or  bromides.  Their  solu- 
tions give,  with  ammonia,  and  with  fixed  alkalies  and 
their  carbonates,  a  brown,  gelatinous  precipitate  of 
sesquioxide,  containing  the  whole  of  the  thallium. 
Hydrochloric  acid  and  soluble  chlorides  or  bromides 
produce  no  precipitate  in  solutions  of  pure  salts  of  the 
sesquioxide ;  but  if  any  protoxide  is  likewise  present 
a  sesquichloride  or  sesquibromide  is  formed.  Chro- 
mate of  potassa  produces  no  precipitate,  except  in  a 
solution  of  sulphate. 

V.  Estimation  and  separation. — Thallium,  when  it 
occurs  in  solution  as  a  salt  of  the  protoxide,  is  most 


THALLIUM.  131 

conveniently  estimated  as  protiodide,  Til,  in  which 
state  it  is  obtained  by  precipitation  with  iodide  of  po- 
tassium. The  precipitate  is  quite  permanent  in  the 
air,  and  at  the  temperature  of  which  it  is  weighed.  It 
is  but  very  slightly  soluble  in  water,  insoluble — or 
nearly  so — in  saline  solutions,  alcohol  of  92  per  cent., 
and  aqueous  ammonia ;  but  perceptibly  soluble  in 
water  containing  free  acids  or  fixed  alkalies.  On  mix- 
ing the  hot  ammoniacal  solution  of  a  protoxide  salt  with 
iodide  of  potassium,  the  thallium  iodide  separates  im- 
mediately as  a  curdy  precipitate,  which,  after  standing 
for  several  hours,  may  be  collected  on  a  weighed  filter, 
and  washed  with  alcohol ;  or,  if  this  is  inadmissible 
with  ammonia,  it  is  then  dried  at  115°,  and  weighed — 
it  contains  49.40  per  cent,  thallium. 

Thallium  may  also  be  estimated  in  the  form  of  pro- 
tosulphate,  but  not  quite  so  exactly  as  by  the  method 
just  described.  The  sulphate  bears  a  dull  red  heat 
without  perceptible  volatilization,  but  is  volatilized  at 
a  bright  red  heat.  Thallium  is  very  completely  pre- 
cipitated from  solutions  of  thallium  salts  by  chloride  of 
platinum  ;  but  the  precipitated  chloroplatinate  is  trou- 
blesome to  manage,  as  it  is  very  finely  divided,  and  is 
apt  to  run  through  the  filter  when  washed  with  water 
or  alcohol. 

In  solutions  of  peroxide  salts  the  thallium  may  be 
estimated  by  reducing  the  peroxide  to  protoxide  salts 
with  an  alkaline  sulphite,  and  then  precipitating  with 
iodide  of  potassium  ;  or  by  precipitating  the  thallium 
with  ammonia  as  sesquioxide,  and  collecting  the  pre- 
cipitate on  a  weighed  filter.  The  separation  of  protox- 
ide from  peroxide  salts  may  be  effected,  at  least  in  the 
case  of  the  chlorides  or  sulphates,  by  first  precipitating 
the  sesquioxide  with  ammonia,  and  then  throwing 
down  the  remaining  portion  of  thallium  from  the  hot 
dilute  filtrate  with  iodide  of  potassium.  The  separa- 


132  THALLIUM. 

tion  may  also  be  effected  by  chloride  of  platinum, 
which  precipitates  only  the  protoxide  salt. 

The  method  of  precipitation  with  iodide  of  potas- 
sium serves  also  to  separate  thallium  from  most  other 
metals,  the  solution  being  first  mixed  with  an  alkaline 
sulphite  to  insure  the  reduction  of  any  peroxide  salt 
that  may  be  present  to  the  state  of  protoxide  salt.  If 
copper  is  present  the  iodide  of  potassium  will  throw 
down  copper  as  well  as  thallium  iodide  ;  but  by  treat- 
ing the  washed  precipitate  with  ammonia,  in  contact 
with  the  air,  copper  will  be  dissolved  out,  and 
the  thallium  will  remain  as  iodide  of  thallium.  The 
separation  of  copper  from  thallium  may  also  be  effect- 
ed, though  not  so  exactly,  by  precipitating  the  copper 
with  sulphuretted  hydrogen  in  an  acid  solution.  The 
same  method  serves  also  to  separate  thallium  fromlead 
and  silver.  The  precipitated  sulphides  are  apt,  how- 
ever, to  curry  down  small  quantities  of  sulphide  of 
thallium. 

Small  quantities  of  thallium  often  occur  in  bismuth 
minerals,  and  preparations  are  made  from  them,  espe- 
cially the  carbonate.  To  detect  the  thallium,  the  dilute 
solution  of  the  substance  is  mixed  with  a  slight  excess 
of  carbonate  of  soda  and  a  small  quantity  of  cyanide  of 
potassium,  then  gently  warmed  and  filtered.  If  the 
bismuth  compound  contained  only  1  pt.  of  thallium  in 
100,000,  the  addition  of  a  few  drops  of  ammonium- 
sulphide  will  produce  a  dark-brown  precipitate  of 
sulphide  of  thallium,  which  gradually  collects  together 
and  may  be  further  examined  by  the  spectroscopic 
method.  From  carbonate  of  bismuth,  thallium  may 
be  easily  dissolved  out  by  digestion  with  cyanide  of 
potassium,  less  completely  with  carbonate  of  soda. 

Volumetric  Estimation. 

Thallium  may  be  estimated  volumetrically  with  per- 
manganate of  potassa  in  the  same  manner  as  iron. 


INDIUM.  133 

For  this  purpose  it  must  be  in  the  state  of  a  chloride, 
or  of  a  protoxide-salt  mixed  with  hydrochloric  acid, 
and  the  solution  must  not  contain  more  than  1  gramme 
of  thallium  in  500  c.c. ;  the  permanganate  solution 
must  be  more  dilute  than  for  the  estimation  of  iron. 
The  titration  of  the  permanganate  may  be  made  with 
pure  iron,  with  thallium,  or  with  a  protoxide-salt  (the 
alum,  for  example);  2  at.  iron  (112  pts.)  correspond  to 
1  at.  thallium  (204  pts.),  inasmuch  as  the  protochloride 
HOI  is  converted  by  oxidation  into  a  trichloride,  HC13, 
so  that  1  at.  thallium  takes  up  the  same  quantity  of 
oxygen  as  2  at.  iron.  The  solution  of  the  protoxide 
salt,  diluted  as  above  mentioned,  is  mixed  with  a  few 
drops  of  hydrochloric  and  a  few  drops  of  sulphurous 
acid,  and  heated  to  the  boiling-point  to  expel  the 
latter ;  then  left  to  cool,  and  mixed  with  the  perman- 
ganate. 


73.  INDIUM. 

This  metal  was  discovered  in  1863  by  Messrs.  Reiqh 
and  Richter,  in  the  zinc  blende  of  Freiberg.  It  has 
been  investigated  since  that  time  by  Mr.  Clement 
Winckler,  from  whose  work  we  borrow  the  follow- 
ing:— 

The  zinc  obtained  from  the  Freiberg  blende  contains 
0.045  per  cent,  of  indium,  as  well  as  small  quantities 
of  lead,  iron,  arsenic,  and  cadmium.  It  was  by  the  aid 
of  ammonia,  in  which  the  oxide  of  indium  is  entirely 
insoluble,  that  Reich  and  Richter  separated  the  indium 
from  the  zinc.  This  process,  which  is  excellent,  be- 
cause the  oxide  of  indium  is  insoluble  in  the  ammonia, 
has  the  inconvenience  of  being  much  too  expensive, 
on  account  of  the  large-  quantities  of  the  reagent  it  is 
necessary  to  employ. 
12 


134  *        INDIUM. 


I. — Separation  of  the  Indium. 

a.  BY  MEANS  OF  ZINC. — The   granulated   zinc   is 
dissolved    in    dilute   sulphuric  or  hydrochloric  acid, 
taking  care  to  leave  a  small  quantity  of  zinc  not  dis- 
solved.    The  solution  is  heated  to  the  boiling  point, 
and  kept  there  until  no  trace  of  gas  is  discernible.     A 
spongy,  metallic  substance  is  obtained  in  this  way, 
consisting  mostly  of  lead,  and  which  contains,  also, 
arsenic,  iron,  cadmium,  and  all  the  indium  of  the  ori- 
ginal zinc,  if  care  has  been  taken  to  leave  in  the  liquid 
an  excess  of  zinc.  It  can  be  shown  that  all  the  indium 
is  precipitated  by  testing  the  filtered  liquid  with  am- 
monia,  adding   enough    to   dissolve   the    precipitate 
formed,  filtering  and  examining  the  residue  with  the 
spectroscope. 

b.  BY  MEANS  OF  ACETATE  OF  SODA. — This  method 
of  separation  depends  upon  the  tendency  of  the  indium 
to  form  basic  salts,  a  property  which  belongs  to  it  as 
much  as  to  the  oxide  of  iron.     It  is  applicable  for  so- 
lutions containing  indium  and  chloride  of  zinc. 

A  little  sulphuric  acid  is  added  to  the  solution,  if 
it  does  not  already  contain  it.  It  is  then  neutralized 
with  carbonate  of  soda  until  the  liquid  remains  cloudy. 
Acetate  of  soda  is  then  poured  upon  it,  and  boiled  for 
some  time.  A  precipitate  is  thus  formed  of  basic  sul- 
phate of  indium,  together  with  iron  and  a  little  oxide 
of  zinc,  which  is  filtered  and  washed.  It  is  preferable 
to  decant  it  on  the  filter,  the  precipitate  being  gelatin- 
ous, and  quickly  filling  the  pores  of  the  filter. 

C.    BY   THE    MEANS   OF    CAEBONATE    OF    BAEYTA. — 

The  oxide  is  completely  precipitated,  even  when  cold, 
from  its  solution  by  the  carbonate  of  baryta ;  the  liquid 
should  be  acidulated  by  either  nitric  or  hydrochloric 
acid.  It  is  mixed  when  cold  with  carbonate  of  baryta 
recently  precipitated,  stirred  for  some  time,  and  then 


INDIUM.  135 

the  mixture  allowed  to  stand;  all  the  indium  will  be 
precipitated  with  a  little,  oxide  of  iron,  but  free  from, 
oxide  of  zinc. 

II. — Purification  of  Indium. 

After  having  separated  by  one  of  the  preceding 
methods  the  oxide  of  indium  from  the  greater  part  of 
the  zinc,  the  metal  is  then  purified.  Winckler  recom- 
mends the  use  of  the  precipitate  obtained  by  process  a. 

This  sponge  is  dissolved  in  nitric  acid,  and  the 
greater  part  of  the  lead  separated  by  the  aid  of  sul- 
phuric acid.  Hydrosulphuric  acid  is  passed  into  the 
filtrate  until  the  lead,  cadmium,  arsenic,  &c.,  are  com- 
pletely precipitated. 

The  hydrosulphuric  acid  is  driven  off  by  boiling. 
The  iron  is  oxidized  by  adding  chlorate  of  potassa  and 
precipitated  by  ammonia.  The  greater  part  of  the 
zinc  remains  in  solution,  the  precipitate  of  oxide  of 
iron  and  oxide  of  indium  contain  very  little  of  it. 

After  washing,  the  precipitate  is  dissolved  on  the 
filter  in  warm  dilute  acetic  acid,  and  the  whole  of  the 
indium  is  precipitated,  at  the  same  time  a  little  of  the 
iron  and  zinc  by  the  hydrosulphuric  acid. 

It  is  very  difficult  to  separate  all  the  iron  and  the 
zinc,  even  by  repeating  the  process  ten  times. 

In  order  to  obtain  absolutely  pure  indium  it  is  better 
to  employ  the  precipitate  obtained  by  the  carbonate 
of  baryta.  The  iron  in  this  case  should  be  in  the  state 
of  protoxide,  because  the  peroxide  of  this  metal  is  pre- 
cipitated by  the  carbonate  of  baryta. 

The  sulphur  of  impure  indium  is  dissolved  in  dilute 
hydrochloric  acid.  It  is  heated  in  order  to  drive  off 
the  hydrosulphuric  acid  dissolved  in  the  liquid,  and  a 
solution  is  obtained  which  contains  iron  in  the  state  of 
protochloride. 

After  cooling,  a  sufficient  quantity  of  carbonate  of 


136  INDIUM. 


is  added,  and  is  left  to  digest  for  twenty-four 
hours  —  stirring  it  frequently: 

The  precipitate  which  contains  all  the  indium  is 
carefully  filtered  and  washed,  while  the  whole  of  the 
iron  and  zinc  are  found  in  the  liquid. 

The  precipitate  is  decomposed  by  sulphuric  acid, 
which  gives  some  sulphate  of  baryta  and  some  sulphate 
of  oxide  of  indium,  from  which  the  ammonia  precipi- 
tates entirely  pure  oxide  of  indium. 

III.  —  Preparation  of  Metallic  Indium. 

The  oxide  of  indium  is  heated  to  a  low  temperature 
in  a  porcelain  crucible,  into  which  a  current  of  hydro- 
gen is  passed.  A  little  indium  is  always  lost,  on 
account  of  the  volatility  of  the  metal.  If  the  gas  is 
passed  slowly  at  first,  in  such  a  manner  that  it  does 
not  burn  between  the  cover  and  the  crucible,  very  little 
of  the  indium  is  lost,  and  the  current  of  gas  can  then 
be  increased  without  fear  of  carrying  off'  much  of  the 
metal.  The  crucible  is  left  to  cool  in  the  current  of 
gas,  and  little  metallic  globules  are  obtained  at  the 
bottom  of  the  vessel.  In  order  to  unite  them  in  one 
mass  fused  cyanide  of  potassium  is  added  —  heated  to 
redness  —  and  the  union  of  the  globules  is  aided  by 
inclining  the  crucible  in  different  directions. 

The  mass  is  freed  from  the  cyanide  of  potassium, 
which  adheres  to  it,  by  washing  with  hot  water. 

IV.  —  Properties  of  Indium. 

The  color  of  indium  is  similar  to  that  of  platinum, 
has  marked  metallic  characteristics,  and  is  much  sof- 
ter than  lead  —  can  be  easily  separated  into  thin  lami- 
na —  it  marks  paper  —  it  does  not  tarnish  on  exposure 
to  the  air  —  it  is  soluble  in  dilute  hydrochloric  and 
sulphuric  acid  ;  but,  when  in  contact  with  concentrated 
sulphuric  acid,  is  given  off  sulphurous  acid.  Nitric 


INDIUM.  137 

acid  oxidizes  it  rapidly.  Heated  to  redness  it  vola- 
tilizes and  barns  with  a  violet  flame,  which  deposits 
a  yellow  coating  on  the  sides  of  the  crucible.  Its 
specific  gravity  at  15°  is  equal  to  7.362.  Its  equiva- 
lent, according  to  Winckler,  is  35.9. 

V. —  Combinations  of  Indium. 

The  oxide  (In  O)  seems  to  be  the  only  combination 
with  oxygen.  It  is  honey-colored,  and  transparent 
when  it  is  prepared  by  the  calcination  of  the  hydrate: 
heated  it  becomes  brown. 

The  calcined  oxide  is  slightly  soluble  in  acids  when 
cold  ;  dissolves  rapidly  in  them  when  heated. 

The  salts  of  indium  are  white.  Zinc  precipitates 
indium  from  its  solution  in  the  form  of  brilliant  scales. 

The  hydrate  of  oxide  of  indium  forms  a  bulky, 
white  precipitate,  which  resembles  aluminum,  and 
yields  like  this  metal  a  horny  mass  when  dry.  It  is 
completely  insoluble  in  ammonia,  potassa,  and  soda. 

The  carbonate  and  phosphate  of  indium  are  white. 

In  the  solutions  of  oxides  of  indium  the  yellow  fer- 
rocyanide  of  potassium  gives  a  white  precipitate.  The 
red  ferridcyanide  and  sulphocyanide  of  potassium, 
gallic  acid,  and  chromate  of  potassa  give  no  precipi- 
tate. 

The  oxalate  of  indium  is  crystalline 

The  sulphate  gives  imperfect  crystals. 

The  nitrate  crystallizes  with  difficulty  in  an  aqueous 
solution. 

The  very  acid  solutions  give  small  prisms  joined  in 
bundles. 

The  sulphide  of  indium  is  separated  in  the  form  of 
a  yellow  gelatinous  precipitate,  which,  when  dried, 
gives  hard  and  brittle  fragments.  The  presence  of 
acids  prevents  the  precipitation  of  indium  by  hydro- 
sulphuric  acid  ;  it  is  not  the  same  with  the  sulphide  of 

12* 


138  TELLURIUM   ORE. 

ammonium.  The  precipitate  obtained  by  this  last  re- 
agent is  insoluble  when  cold  in  an  excess  of  sulphide  of 
ammonium:  it  dissolves,  on  the  contrary,  when  heated 
in  this  liquid.  By  cooling  the  sulphide  is  precipita- 
ted ;  but  it  is  white  in  this  case,  and  is  probably  a 
hydrate. 


74.  TELLURIUM  OEE. 

The  Transylvania  powdered  ore  contains  graphic 
and  foliated  tellurium-ore;  i.e.,  the  tellurides  of  gold, 
silver,  lead,  and  sulphide  of  tellurium,  mixed  with 
various  other  minerals. 

In  order  to  remove  a  great  portion  of  the  gangue, 
the  finely-powdered  ore  is  mixed  with  dilute  hydro- 
chloric acid,  with  which  it  is  left  in  contact  until  no 
farther  disengagement  of  carbonic  acid  takes  place, 
the  whole  being  frequently  agitated  by  stirring.  It  is 
then  washed  and  dried.  Various  methods  can  be 
used  to  extract  the  tellurium  and  to  recover  at  the 
same  time  the  noble  metals. 

I.  The  ore  is  dissolved  in  nitro-hydrochloric  acid, 
with  the  precaution,  however,  that  the  nitric  acid  is 
only  gradually  added,  and  in  such  quantities  that  it 
may  all  be  decomposed.  When  the  mass  has  become 
completely  white,  and  all  the  nitric  acid  has  been  ex- 
pelled by  heat,  some  sulphuric  and  tartaric  acids  are 
added,  the  former  to  insure  the  complete  precipitation 
of  the  lead  and  the  decomposition  of  the  tellurite  of 
lead,  the  latter  to  prevent  the  precipitation  of  tellurous 
acid;  after  this,  about  twice  its  bulk  is  added  to  the 
mass.  When  completely  cold,  the  solution  is  filtered 
off  and  the  residue  washed.  The  latter  consists  of 
quartz,  heavy  spar,  sulphate  of  lead,  and  a  small  quan- 
tity of  chloride  of  silver,  which  may  be  extracted  by 
amii.onia. 


TELLURIUM   ORE.  139 

From  the  solution  the  gold  is  precipitated  by  a  con- 
centrated solution  of  sulphate  of  protoxide  of  iron. 
When  the  metal  has  subsided,  it  is  washed  and  ignited. 

The  liquor  filtered  off  from  it  is  considerably  con- 
centrated by  evaporation  in  a  flask,  allowed  to  cool, 
and  mixed  with  a  solution  of  an  alkaline  sulphite, 
when  the  tellurium  is  precipitated  as  a  gray  powder. 
After  standing  for  twelve  or  twenty-four  hours  it  is 
filtered  off,  and  washed,  first  with  dilute  sulphurous 
acid,  and  then  with  water.  The  solution  must  be 
made  strongly  acid  in  every  case,  to  insure  the  com- 
plete precipitation  of  the  tellurium. 

Gold  and  tellurium  may  also  be  precipitated  together 
by  an  alkaline  sulphite,  and  the  latter  metal  then  ex- 
tracted by  means  of  nitric  acid.  The  filtered  liquid  is 
again  evaporated  to  a  small  bulk,  and  mixed  with  an 
alkaline  sulphite,  when,  in  most  cases,  a  farther  quan- 
tity of  tellurium  is  obtained. 

II.  The  ore,  freed  from  most  of  the  gangue  by 
means  of  hydrochloric  acid,  is  intimately  mixed  with 
twice  its  weight  of  bisulphate  of  potassa  ;  4  to  6  times 
its  quantity  of  bisulphate  of  potassa  is  then  fused  in  a 
capacious  Hessian  crucible  at  a  gentle  heat,  and  into 
the  fusing  salt  the  above-mentioned  mixture  is  intro- 
duced by  small  portions  at  a  time,  waiting  between 
each  addition,  until  the  frothing  of  the  mass  has  sub- 
sided. When  this  has  ceased,  and  a  sample  of  the 
mass  being  taken  out  appears  quite  white,  the  fused 
mass  is  poured  off  from  the  gold,  which  has  settled  at 
the  bottom  of  the  crucible.  The  remainder  of  the  salt 
is  then  washed  out  of  the  crucible  with  hot  water  con- 
taining sulphuric  acid,  and  the  gold  collected. 

The  mass  which  was  poured  off  is  then  dissolved  in 
this  water,  with  a  farther  addition  of  sulphuric  acid, 
the  solution  filtered  off  from  the  sulphate  of  lead,  &c., 
and  then  the  silver  precipitated  by  means  of  hydro- 
chloric acid. 


140  TELLURIUM   ORE. 

The  filtered  solution  is  concentrated  by  evaporation, 
and  the  tellurium  precipitated  by  sulphurous  acid. 

The  tellurium  thus  obtained  is  not  quite  pure.  In 
order  to  purify  it,  it  is  distilled  in  a  tube  of  hard  glass, 
at  a  strong  red  heat,  in  a  current  of  hydrogen.  The 
traces  of  lead  and  copper  remain  behind  as  tellurides, 
and  a  slight  mixture  of  selenium  is  carried  off  by  the 
gas. 

Tellurium  containing  selenium  may  be  easily  sepa- 
rated from  it  completely  by  fusing  it  for  some  time  in 
hydrogen  gas.  If  the  two  are  in  solution  they  are 
precipitated  by  sulphurous  acid  and  the  selenium, 
separated  by  a  solution  of  cyanide  of  potassium,  in 
which  it  is  soluble.  The  tellurium  remains  undissolved. 
Selenium  is  precipitated  from  this  solution  by  acids. 

The  pulverulent  tellurium  may  be  fused  easily  into 
a  button,  if  covered  with  a  mixture  of  9  parts  of  chlo- 
ride of  potassium  and  7  parts  of  chloride  of  sodium. 

Accurate  quantitative  analyses  of  pure  graphic  tel- 
lurium and  foliated  tellurium  are  best  made  by  means 
of  chlorine  gas,  as  in  the  case  of  tetrahedrite.  Tellurium 
is  volatilized  in  this  process  as' chloride  of  tellurium  ; 
it  requires,  however,  a  very  wide  tube,  on  account  of 
its  being  very  bulky. 

From  the  telluride  of  bismuth  (tetradymite)  of 
Schemnitz,  in  Hungary,  the  tellurium  is  best  obtained 
by  the  following  process:  The  finely-divided  ore  is 
intimately  mixed  with  3  times  its  weight  of  ignited 
cream  of  tartar,  and  exposed  to  a  moderate  red  heat 
in  a  covered  crucible  during  one  hour,  when  all  the 
tellurium  is  converted  into  telluride  of  potassium,  and 
the  bismuth  separated.  The  cold  mass  is  reduced  to 
powder,  thrown  on  a  filter,  and  completely  washed 
with  cold  water  which  has  been  freed  from  air  by 
boiling.  The  dark-red  solution  of  telluride  of  potas- 
sium passing  through  the  filter,  when  exposed  to  the 
air,  soon  deposits  all  the  tellurium  in  the  form  of 


NATROL1TE.  141 

a  gray  powder.  This  method  is  not  applicable  to 
graphic  and  foliated  tellurium  ore.  It  is  very  useful, 
however,  for  the  extraction  of  pure  tellurium  from  the 
crude  tellurium  of  Vienna,  which  contains  copper,  iron, 
lead,  antimony  and  arsenic.  For  this  purpose,  also,  a 
mixture  of  4  parts  of  dry  carbonate  of  soda  and  1  part 
of  powdered  coal  may  be  used  ;  2  parts  of  this  mixture 
are  taken  for  1  part  of  the  finely  pulverized  metal ; 
coarsely  powdered  coal  is  placed  in  the  bottom  of  the 
crucible,  the  mass  pressed  down  upon  this  and  then 
covered  with  the  same  kind  of  coal. 

The  tellurium  in  the  filtrate  can  be  separated  from 
coal,  &c.,  by  using  an  excess  of  hypochlorite  of  soda. 
After  long  digestion  with  this  reagent,  the  mixture  is 
heated  gradually  to  ebullition,  the  chloric  acid  decom- 
posed by  evaporation  with  hydrochloric  acid,  and  then 
the  tellurium  precipitated  by  sulphurous  acid. 


75.  NATROLITE  *  THOMSONITE,f  &c. 

The  amount  of  water  is  determined  by  igniting  a 
weighed  quantity  of  the  material,  which  has  previously 
been  dried  at  100°. 

The  finely-divided,  unignited  mineral,  dried  at  100, 
is  mixed  in  a  porcelain  dish  with  moderately  strong 
hydrochloric  acid,  and  digested  with  it,  with  constant 
stirring,  until  completely  converted  into  a  gelatinous 
mass,  and  all  the  mineral  is  dissolved. 

This  mass  is  then  evaporated  to  complete  dry  ness, 
being  carefully  stirred,  in  order  to  render  the  silica 

*  A1203,  3  Si02,  NaO,  2  HO. 

t  A1203,  2  Si02,  (fCaO+^NaO),  2£  HO. 


142  NATRGLITE. 

insoluble;  the  evaporation  is  best  effected,  at  least 
towards  the  end,  in  th'e  water-bath. 

The  remaining  salt  mass  is  moistened  with  hydro- 
chloric acid,  after  some  time  a  little  hot  water  is  poured 
upon  it,  and  the  silica  filtered  off,  washed  with  hot 
water,  dried,  carefully  ignited  and  weighed. 

From  the  filtered  solution  the  alumina  is  precipitated 
by  sulphide  of  ammonium,  and  treated  as  in  No.  16. 

When  the  zeolite  contains  sesquioxide  of  iron,  the 
alumina  is  colored  more  or  less  black  or  greenish- 
black  by  sulphide  of  iron.  The  iron  is  separated  from 
it  as  in  No.  21. 

The  solution  filtered  from  the  alumina  is  evaporated 
to  a  small  bulk,  in  a  dish,  transferred  to  a  weighed 
platinum  crucible,  and  carefully  evaporated  to  drjmess. 
The  saline  mass  is  gradually  heated  till  the  sal-ammo- 
niac is  volatilized,  and  finally  heated  to  redness,  the 
cover  being  loosely  placed  upon  the  mouth  of  the  cru- 
cible. The  residue  is  chloride  of  sodium. 

The  silicic  acid  obtained  in  the  decomposition  of  a 
silicate,  especially  if  it  separate  rather  in  a  pulverulent 
than  a  gelatinous  state,  must  always  be  examined  as 
to  its  purity,  since  it  may  sometimes  contain  other  con- 
stituents of  the  mineral,  especially  alumina,  or  even 
portions  of  the  undecornposed  mineral  itself. 

Pure  silicic  acid  must  entirely  dissolve  in  a  boiling 
solution  of  carbonate  of  soda.  An  insoluble  residue 
indicates  an  impurity,  which  should  be  filtered  off  arid 
examined.  It  is  preferable,  however,  to  fuse  such 
silicic  acid  with  3  parts  of  carbonate  of  potassa  and 
soda,  and  to  treat  it  as  in  No.  79  or  80. 

Silicic  acid,  if  perfectly  pure,  when  dissolved  in 
hydrofluoric  acid,  in  a  platinum  capsule,  entirely  dis- 
appears on  evaporation.  Should  there  be  any  residue, 
it  is  again  treated  with  hydrofluoric  acid,  afterwards 
with  concentrated  sulphuric  acid,  evaporated  to  dry- 


ILVAITE.  143 

ness,  and  examined.     It  sometimes  consists  of,  or  con- 
tains titanic  acid. 


76.  ILVAITE .* 

The  finely-powdered  mineral  is  moistened  with  a 
suitable  quantity  of  water,  in  a  porcelain  capsule,  some 
concentrated  hydrochloric  acid  and  a  little  nitric  acid 
added,  and  the  whole  heated  to  complete  gelatinization. 
The  mass  is  then  evaporated  to  perfect  dryness  on  a 
water-bath,  during  which  operation  it  is  frequently 
stirred. 

The  dry  mass  is  moistened  with  concentrated  hydro- 
chloric acid,  then  dissolved  in  chlorine  water,  the 
silicic  acid  filtered  off',  and  treated  in  the  usual  man- 
ner (No.  75). 

From  the  solution,  diluted  with  the  washing-water, 
the  sesquioxide  of  iron  is  precipitated  by  ammonia, 
the  precipitate  allowed  to  subside  in  a  covered  vessel, 
and  rapidly  filtered  off;  the  solution  should  first  be 
passed  through  the  filter,  which  is  kept  covered,  as 
far  as  possible,  to  prevent  absorption  of  qarbonic  acid. 
The  precipitate  is  washed  by  means  of  the  wash-bottle 
arranged  for  the  purpose,  dried,  ignited,  and  weighed 
as  sesquioxide  of  iron. 

The  filtrate  from  the  sesquioxide  of  iron  is  acidu- 
lated with  hydrochloric  acid,  concentrated  by  evapo- 
ration, in  a  flask,  mixed  with  ammonia,  the  lime  pre- 
cipitated by  oxalate  of  ammonia,  and  treated  as  in 
No.  12. 

The  mineral  contains  about  1.5  per  cent,  of  protox- 
ide of  manganese,  and  0.5  per  cent,  of  alumina,  both  of 

*  The  compact  variety  from  Elba  is  not  rare.  It  may  also  be 
obtained  artificially  by  fusing,  together  6  parts  of  forge-scales,  3 
parts  of  fine  white  quartz-sand,  and  1^  parts  of  calcined  marble,  at 
a  strong  white  heat. 


CHRYSOLITE. 

which  are  contained  in  the  precipitated  sesquioxide  of 
iron,  and  must  be  separated  from  it  as  in  Nos.  21  and 
25. 

About  1.5  per  cent,  of  water  is  also  present  as  an 
unessential  constituent ;  its  quantity  may  be  ascer- 
tained by  ignition  in  a  covered  crucible. 

In  order  to  ascertain  directly  the  relative  amounts 
of  protoxide  and  sesquioxide  of  iron,  the  process  de- 
scribed in  No.  24  must  be  followed. 


77.  CHRYSOLITE  (OLIVINE). 
2  (MgO,  FeO),  Si02. 

The  very  finely-powdered  mineral  is  decomposed 
by  digestion  with  concentrated  hydrochloric  acid,  the 
mass  dried  upon  the  water-bath,  moistened  with  con- 
centrated hydrochloric  acid,  and,  after  some  time, 
mixed  with  water  and  filtered  from  the  separated 
silica. 

Small  amounts  of  copper  and  tin,  which  are  con- 
tained in  many  specimens  of  olivine,  are  detected  and 
separated  by  mixing  the  solution  with  saturated  sul- 
phuretted hydrogen-water,  until  it  smells  strongly, 
and  allowing  it  to  stand  for  some  time  in  a  closed 
vessel. 

The  solution  filtered  from  the  precipitate  is  concen- 
trated by  evaporation,  some  chlorate  of  potassa  being 
added  to  peroxidize  the  iron. 

The  sesquioxide  of  iron  may  be  precipitated  by  an 
excess  of  ammonia,  and  the  magnesia  separated  from 
it  by  boiling  the  solution  until  all  the  free  ammonia 
is  expelled,  when  the  sesquioxide  of  iron  remains,  and 
may  be  filtered  off'. 

This  filtrate  contains,  besides  magnesia,  a  small  quan- 
tity of  protoxide  of  manganese  and  protoxide  of  nickel, 


DATOLITE.  145 

which  latter  is  wanting  only  in  the  olivine  of  meteoric 
iron.  These  are  precipitated  by  sulphide  of  ammo- 
nium, an  excess  of  which  is,  as  far  as  possible,  to  be 
avoided.  The  precipitate  is  not  to  be  filtered  oft*  until 
it  has  separated  so  as  to  leave  the  solution  perfectly 
clear ;  it  may  then  be  washed  with  very  dilute  sulphide 
of  ammonium.  If  both  metals  are  present  only  in 
small  quantities,  the  sulphide  of  manganese  may  then 
be  separated  from  the  sulphide  of  nickel  by  treating  it, 
upon  the  filter,  with  very  dilute  hydrochloric  acid,  in 
which  the  sulphide  of  nickel  is,  practically,  insoluble. 
The  small  quantity  of  sulphide  of  nickel  is  then  ignited 
in  the  air,  and  weighed  as  protoxide.  The  manganese  is 
precipitated  from  the  solution  by  carbonate  of  soda,  at 
a  boiling  heat. 

The  liquid  filtered  from  the  precipitate  produced  by 
sulphide  of  ammonium,  is  mixed  with  ammonia,  and 
the  magnesia  precipitated  by  phosphate  of  soda  (No.  6). 

In  the  analysis  of  olivine,  the  iron,  when  converted 
into  sesquioxide,  may  also  be  separated  from  the  other 
bases  by  succinate  of  ammonia  (No.  21). 


78.  DATOLITE. 
(3  CaO,  3HO,  B03)  Si02. 

For  the  determination  of  water,  a  weighed  quantity 
of  the  mineral  is  heated  to  bright  redness. 

If  the  unignited  mineral,  in  a  finely-powdered  state, 
be  digested  with  moderately  strong  hydrochloric  acid, 
it  becomes  a  gelatinous  mass.  If  the  mixture  be  heated 
to  boiling,  and  filtered  while  hot,  boracic  acid  separates 
from  the  solution  in  crystals. 

The  finely-powdered  mineral  is  decomposed  by  di- 
gestion with  hydrochloric  acid,  and  the  mass  evaporated 
to  dryness,  when  a  great  part  of  the  bqracic  acid  is 


146  ULEXITE. 

volatilized ;  after  exposure  for  a  considerable  time  to 
a  temperature  of  100°,  the  residue  is  heated  with  water 
containing  hydrochloric  acid,  the  silicic  acid  filtered 
oft)  washed,  dried  and  ignited. 

The  filtrate  is  neutralized  with  ammonia,  and  the 
lime  precipitated  by  oxalate  of  ammonia  (No.  12). 

By  this  process  the  boracic  acid  cannot  be  deter- 
mined directly  but  only  by  difference,  because  a  large 
part  of  it  volatilizes  during  evaporation.  In  order  to 
make  a  direct  determination,  the  mineral  is  decomposed 
by  hydrochloric  acid,  or  a  retort  furnished  with  a  re- 
ceiver, distilled  to  dryness,  and  the  distillate  containing 
the  boracic  acid  poured  back  upon  the  residue,  with 
which  it  is  digested  for  some  time,  and  then  filtered 
from  the  silicic  acid.  The  lime  is  then  precipitated 
by  a  large  excess  of  oxalate  of  potassa,  filtered,  and 
the  filtrate  concentrated  by  evaporation.  From  this 
the  boracic  acid  is  precipitated  as  a  double  fluoride  of 
boron  and  potassium.  For  this  purpose  it  is  placed  in 
a  platinum  dish  with  a  little  potassa,  then  mixed  with 
a  small  excess  of  hydrofluoric  acid,  and  evaporated  to 
dryness.  For  the  separation  of  the  other  salts,  the 
mass  is  treated  with  a  moderately  concentrated  solution 
of  acetate  of  potassa,  allowed  to  stand  for  some  time, 
and  the  double  fluoride  of  boron  and  potassium  thrown 
upon  a  weig'hed  filter,  and  washed  with  the  solution  of 
the  acetate.  The  acetate  of  potassa  is  then  washed  out 
with  alcohol.  The  double  fluoride  is  dried  at  100° 
and  weighed. 


79.  ULEXITE. 
.  NaO,  2BoO3+2  (CaO,  2BoO3)  +18HO. 

After  determination  of  the  water  the  mineral  is  dis- 
solved in  hydrochloric  acid,  neutralized  with  ammonia, 


ORTHOCLASE.  1  \1 

and  the  lime  precipitated  by  oxalate  of  ammonia.  The 
filtered  solution  is  concentrated  by  evaporation,  and 
the  boracic  acid  separated  as  in  No.  78  as  a  double 
fluoride  of  boron  and  potassium. 

For  the  determination  of  the  soda  another  portion  is 
dissolved,  the  lime  precipitated  by  oxalate  of  ammonia, 
the  filtrate  evaporated  to  dryness,  and  heated  to  drive 
oft'  the  ammoniacal  salts.  The  mass  is  then  digested 
with  strong  hydrofluoric  acid,  evaporated  to  dryness, 
digested  with  concentrated  sulphuric  acid,  and  evapo- 
rated to  drive  off  the  fluoride  of  boron.  The  sulphate 
of  soda  is  finally  ignited,  a  piece  of  carbonate  of  am- 
monia being  held  in  the  crucible. 


80.  ORTHOCLASE. 
KO,Si02+Al203,3Si02. 

I.  The  very  finely-powdered  and  levigated  mineral, 
dried  at  about  200°,  is  very  intimately  mixed,  in  a 
capacious  platinum  crucible,  with  4  or  5  parts  of  car- 
bonate of  baryta ;  the  crucible  is  then  inclosed  in  an 
earthen  crucible,  which  is  placed  in  a  wind-furnace 
with  a  good  draught,  and  exposed  for  at  least  half  an 
hour  to  an  intense  white  heat,  so  that  the  contents  may 
be  firmly  aggregated  into  a  cinder-like  mass.  The 
decomposition  takes  place  more  rapidly,  and  with 
greater  certainty,  when  the  crucible  is  exposed  to  a 
blowpipe  flame,  so  that  the  mass  fuses  completely. 

Or  the  mineral  is  mixed,  in  a  silver  crucible,  with 
4  parts  of  hydrate  of  baryta,  previously  freed  by  heat 
from  its  water  of  crystallization,  and  the  mixture  heated 
to  fusion. 

The  mass  is  then  turned  out  of  the  crucible  into  a 
capacious  dish,  a  quantity  of  water  poured  over  it,  and 
hydrochloric  acid  gradually  added  in  slight  excess, 


148  ORTIIOCLASE. 

until,  with  the  aid  of  a  gentle  digestion,  it  is  com- 
pletely decomposed  and  dissolved,  with  exception  of 
some  gelatinous  silicic  acid  which  is  separated.  The 
whole  solution  is  then  evaporated  to  perfect  dryness, 
in  order  to  render  the  silicic  acid  insoluble,  the  eva- 
poration being  conducted  towards  the  last  upon  a 
water-bath,  with  constant  stirring. 

The  saline  mass  is  afterwards  moistened  with  hydro- 
chloric acid,  a  proper  proportion  of  water  added,  and, 
after  digestion,  the  silica  filtered  off,  washed,  thoroughly 
dried,  ignited,  and  weighed  in  a  covered  crucible. 

From  the  solution  the  baryta  is  precipitated  by 
gradual  and  cautious  addition  of  dilute  sulphuric  acid, 
a  great  excess  of  which  is  to  be  carefully  avoided  ;  the 
sulphate  of  baryta  is  then  filtered  off  and  washed.  (8ee 
No.  3.) 

The  filtrate  is  concentrated,  if  need  be,  by  evapora- 
tion, the  alumina  precipitated  by  sulphide  of  ammo- 
nium, and  treated  as  in  No.  16. 

The  liquid  filtered  from  the  alumina  is  evaporated 
to  dryness,  and  the  dry  mass  ignited  to  expel  the  arn- 
rnoniacal  salts.  This  process  requires  so  much  the 
more  care,  to  avoid  spirting,  the  more  sulphate  of  am- 
monia it  contains,  in  consequence  of  the  careless  addi- 
tion of  sulphuric  acid. 

At  the  end  of  the  operation,  in  order  to  convert  any 
alkaline  bisulphate  into  neutral  sulphate,  a  fragment  of 
carbonate  of  ammonia  is  held  in  the  covered  crucible. 

The  residue  is  sulphate  of  potassa,  and  is  weighed 
as  such.  Should  soda  also  be  present  in  the  mineral, 
the  residue  must  be  treated  as  in  No.  4. 

Another  method  consists  in  precipitating  most  of 
the  baryta  from  the  original  solution  by  gradually 
and  cautiously  adding  dilute  sulphuric  acid;  the  rest 
of  the  baryta,  together  with  the  alumina,  is  then  pre- 
cipitated by  a  mixture  of  carbonate  of  ammonia  and 
free  ammonia,  added  in  slight  excess. 


ORTHOCLASE.  149 

After  twenty-four  hours,  the  precipitate  is  filtered 
off,  washed,  the  alumina  (together  with  the  baryta) 
extracted  by  dilute  hydrochloric  acid,  precipitated  by 
freshly-prepared  sulphide  of  ammonium,  and  rapidly 
washed,  with  as  little  exposure  to  air  as  possible. 

The  liquid  containing  the  alkali,  filtered  off'  from 
the  precipitate  produced  by  carbonate  of  ammonia,  is 
concentrated  by  evaporation,  acidified  with  hydro- 
chloric acid,  evaporated  to  dryness,  and  the  saline  mass 
heated  in  a  covered  crucible  ultimately  to  redness ;  the 
residue  is  chloride  of  potassium  (or  chloride  of  sodium). 
It  must  be  tested  for  baryta  with  sulphuric  acid,  since, 
carbonate  of  baryta  is  not  absolutely  insoluble,  and 
would  have  been  converted  into  chloride  of  barium  by 
ignition  with  salamrnoniac. 

II.  A  second  method  of  decomposing  feldspar  is  that 
with  hydrofluoric  acid.  The  levigated  mineral  is  placed 
in  a  platinum  dish,  or  in  a  capacious  platinum  crucible, 
mixed  with  a  suitable  quantity  of  fuming  hydrofluoric 
acid,  and  digested  with  it  to  complete  decomposition. 

Or  the  mineral  may  be  spread  out  in  a  shallow  plati- 
num capsule,  moistened  with  water,  and  exposed_for  a 
long  time  to  the  vapor  of  hydrofluoric  acid,  in  an  ap- 
propriate leaden  vessel  closed  with  a  lid.  The  hydro- 
fluoric acid  is  evolved  from  powdered  fluor-spar,  which 
is  placed  at  the  bottom  of  the  vessel,  moistened  with 
concentrated  sulphuric  acid,  and  gently  heated. 

The  mineral  is  however  most  easily  decomposed  by 
fluoride  of  ammonium.  One  part  of  the  mineral  is 
mixed  with  about  six  parts  of  the  fluoride  with  a  little 
water,  digested  for  some  time  and  then  raised  to  a  low 
red  heat. 

When  the  decomposition  of  the  feldspar  is  com- 
pleted, the  mass  is  gradually  and  cautiously  mixed 
with  pure  concentrated  sulphuric  acid,  and  evaporated, 
slowly  and  carefully,  to  dryness.  All  the  fluorine  and 
silicon  are  thus  expelled,  and  after  the  volatilization  ot 

13* 


150  GARXET. 

the  excess  of  sulphuric  acid,  the  bases  remain  as  sul- 
phates. 

The  dry  mass  is  moistened  with  concentrated  sul- 
phuric acid,  and  after  a  little  time  mixed  with  water, 
in  which,  if  the  decomposition  be  complete,. it  should 
entirely  dissolve. 

From  this  solution  the  alumina  and  alkalies  are 
separated  as  directed  above. 

A  small  quantity  of  iron,  which  is  frequently  present, 
is  to.be  sought  in  the  alumina. 

In  the  analysis  of  a  feldspar  containing  lime  (labra- 
rlorite,  anorthite).  the  latter  is  precipitated,  after  the 
separation  of  the  alumina,  by  oxalate  of  ammonia. 

When  petalite  and  spodumene  are  analyzed  by  the 
above  methods,  a  mixture  of  salts  of  soda  and  lithia  is 
obtained  at  last,  and  must  be  analyzed  as  in  the  case  of 
triphylline. 

III.  Silicates  are  easily  decomposed  by  acids,  if 
melted  to  a  glass  with  a  small  quantity  of  precipitated 
carbonate  of  lime  in  a  platinum  crucible  before  the 
gas  blowpipe.  One  part  of  feldspar  is  mixed  with 
0.4  parts  of  carbonate  of  lime. 

In  order  to  find  the  amount  of  alkalies  in  silicates 
not  easily  decomposed  by  acids,  they  are  mixed  with 
five  to  six  of  carbonate  of  lime  and  about  three-fourths 
chloride  of  ammonium  and  ignited,  when  the  alkali 
may  be  extracted  with  water. 


81.  PYROXENE,  AMPHIBOLE,  GARNET,  IDOCRASE, 
EP1DOTE. 

Silcates  of  CaO,  MgO,  FeO,  MnO  and  Al2Or 

The  very  finely-powdered  mineral  must  be  decom- 
posed by  fusion  with  four  parts  of  carbonate  of 
potassa  and  soda. 


BERYL.  151 

The  mass  is  softened  with  water,  dissolved  in 
hydrochloric  acid,  the  silica  rendered  insoluble  by 
evaporation,  as  in  the  analysis  of  feldspar;  the  dry 
mass  moistened  with  hydrochloric  acid,  and  a  little 
nitric  acid,  warmed,  diluted,  and  the  silicic  acid 
filtered  off. 

The  solution  is  then  neutralized  by  carbonate  of 
soda,  acetate  of  soda  added  and  heated  to  boiling. 
The  iron  and  alumina  are  precipitated,  and  may  be 
separated  by  hyposulphite  of  soda,  as  in  No.  21. 

The  filtrate,  which  contains  acetates  of  lime,  mag- 
nesia, and  manganese  is  saturated  while  hot  with 
chlorine  gas,  which  precipitates  the  manganese.  After 
ignition  it  is  weighed  as  MnO,  Mn2O3.  If  the  fluid 
has  been  colored  red  by  the  formation  of  perman- 
ganic acid,  ammonia  is  added,  and  then  boiled  until 
the  color  is  destroyed.  The  lime  and  magnesia  are 
separated  in  the  filtrate  as  in  No.  12. 

These  and  all  similar  minerals,  not  attacked  by  hy- 
drochloric acid,  may  likewise  be  conveniently  decom- 
posed by  hydrofluoric  acid;  in  which  case,  however, 
the  silica  must  be  determined  by  loss.  (See  Ortho- 
clase.) 


82.  BERYL. 
Be/),,  2  SiO2  +  A1203,  2  Si02. 

The  very  finely-powdered  mineral,  previously  well 
dried,  is  fused  in  a  platinum  crucible  with  4  times  its 
weight  of  carbonate  of  potassa  and  soda  (see  No.  10) ; 
the  mass  is  softened  with  water,  digested  with  excess 
of  hydrochloric  acid  until  the  decomposition  is  com- 
plete, and  evaporated  to  perfect  dry  ness  to  render  the 
silica  insoluble.  The  residue  is  moistened  with  hydro- 
chloric acid,  and  treated  with  warm  water;  the  silica 


152  BERYL. 

is  then  filtered  off,  the  solution  concentrated  by  evapo- 
ration, and  dropped  very  gradually,  with  constant  stir-' 
ring,  into  an  excess  of  a  warm  concentrated  solution 
of  carbonate  of  ammonia,  which  precipitates  the  alu- 
mina, and  dissolves  the  berylla  (glucina).  When  the 
precipitate  has  been  digested  for  some  time  with  the 
solution  in  a  closed  vessel,  the  solution  is  filtered  off, 
boiled  for  a  long  time,  until  the  greater  part  of  the 
carbonate  of  ammonia  is  expelled,  slightly  acidified 
with  hydrochloric  acid,  digested  for  some  time  to 
expel  the  carbonic  acid,  and  the  glucina  finally  pre- 
cipitated by  caustic  ammonia. 

Pure. glucina  may  be  prepared  in  the  following 
manner.  The  mineral  is  heated  to  redness,  and  then 
thrown  into  cold  water,  when  it  may  be  more  easily 
pulverized.  7  parts  of  the  powder  are  mixed  with 
13  parts  of  finely-powdered  fluor  spar,  and  18  parts  of 
concentrated  sulphuric  acid,  and  warmed  until  no 
more  fluoride  of  silicium  is  given  off.  The  mass  is 
then  gently  ignited,  digested  for  some  time  with  water, 
and  the  sulphate  of  lime  filtered  off.  2  parts  of  sul- 
phate of  potassa  are  then  added  and  the  solution 
evaporated  to  crystallization,  when  the  greater  part  of 
the  alumina  crystallizes  as  alurn.  Acetate  of  soda  is 
then  added  to  the  solution,  and  by  boiling  the  remain- 
der of  the  alumina  and  the  sesquioxide  of  iron  are 
precipitated.  The  glucina  is  precipitated  from  the  fil- 
tered solution  by  ammonia. 

If  hyposulphite  of  soda  precipitates  alumina  alone, 
and  no  glucina,  in  a  neutral  solution  of  the  two  ba^es, 
this  method  may  be  used  for  their  separation.* 

*  See  Silliman's  Journal,  vol.  xxxvi.,  Prof.  C.  A.  Joy  on  Glu- 
cinum  and  its  Compounds. 


TOPAZ.  153 

83.  TOPAZ.* 

6  (3  A1203,  2  SiO2)  +  (3Al2F3  +  2  SiFJ. 

At  a  very  intense  white  heat,  the  topaz  loses  all  its 
fluorine  in  the  form  of  tetrafluoride  of  silicon.  (23  per 
cent.) 

When  fused,  in  the  state  of  very  fine  powder,  with 
4  times  its  weight  of  anhydrous  carbonate  of  soda,  it 
is  decomposed,  with  formation  of  fluoride  of  sodium, 
which  is  extracted  by  water.  Before  filtering  off  the 
residual  silicate  of  alumina,  however,  the  solution  should 
be  digested  with  some  carbonate  of  ammonia,  in  order 
to  precipitate  any  small  quantities  of  alumina  aad 
silica  which  may  have  been  dissolved. 

The  residue  is  then  filtered  off,  washed  with  dilute 
carbonate  of  ammonia,  and  farther  treated  as  in  No.  75. 

The  alkaline  filtrate  is  concentrated  and  freed  from 
ammonia  by  evaporation,  and  the  greater  part  of  the 
carbonate  of  soda  neutralized  by  nitric  acid,  so  that 
some  carbonate  may  still  remain  undecomposed.  The 
solution  is  then  mixed  with  chloride  of  calcium,  which 
precipitates  a  mixture  of  carbonate  of  lime  and  fluo- 
ride of  calcium.  When  the  precipitate  has  separated, 
by  the  aid  of  a  gentle  heat,  it  is  filtered  off,  washed, 
and  ignited.  The  carbonate  of  lime  is  then  dissolved 
in  dilute  acetic  acid,  the  solution  evaporated  to  dry  ness 
on  a  water-bath  to  expel  the  excess  of  acid,  and  the 
acetate  of  lime  extracted  from  the  dry  mass  with  hot 
water.  The  residual  fluoride  of  calcium  is  filtered  off, 
washed,  dried,  ignited,  and  weighed.  If  the  precipitate 
of  carbonate  of  lime  and  fluoride  of  calcium  had  not 
been  ignited  previously  to  the  treatment  with  acetic 
acid,  the  fluoride  would  have  entered  the  pores  of  the 
filter,  and  the  filtrate  would  have  been  turbid. 

*  Defective  crystals  of  Brazilian  topaz  may  frequently  be  ob- 
tained at  a  cheap  rate. 


154  FLUORITE. 

84.  FLUORITE. 
CaF. 

A  weighed  quantity  of  the  finely-powdered  mineral 
is  mixed,  in  a  platinum  crucible,  with  concentrated 
sulphuric  acid,  and  heated  until  all  the  hydrofluoric 
acid  is  expelled,  and  the  greater  excess  of  sulphuric 
acid  volatilized.  The  residual  sulphate  of  lime  is  then 
mixed  with  alcohol,  filtered  off,  washed  with  alcohol, 
ignited  and  weighed.  Or  it  may  be  dissolved  in  water 
containing  hydrochloric  acid,  the  solution  mixed  with 
ammonia,  and  the  lime  precipitated  by  oxalate  of 
ammonia. 

The  fluorine  is  determined  from  the  loss.  In  order 
to  estimate  it  directly,  the  decomposition  must  be  effected 
in  a  platinum  retort,  the  vapors  of  hydrofluoric  acid 
conducted  into  solution  of  carbonate  of  soda,  and  the 
fluorine  precipitated  from  the  solution  by  chloride  of 
calcium,  as  in  the  analysis  of  topaz. 

Or  the  very  finely-powdered  mineral  maybe  mixed 
with  an  excess — that  is,  with  at  least  an  equal  weight — 

Fig.  15. 


CRYOLITE.  155 

of  finely -powdered  silicic  acid  (that  prepared  from  tetra- 
^fluoride  of  silicon  is  the  best),  the  mixture  introduced 
into  an  apparatus  similar  to  that  employed  in  alka- 
limetry, and  the  sulphuric  acid,  which  must  for  this 
purpose  be  very  concentrated,  allowed  to  flow  upon  it. 
With  the  aid  of  a  gentle  heat,  tetrafluoride  of  silicon  is 
formed,  which  is  allowed  to  escape  in  the  gaseous  state 
through  a  tube  filled  with  chloride  of  calcium;  the 
last  portions  are  withdrawn  from  the  apparatus  by 
sucking  air  through  it,  for  which  purpose,  there  is 
attached  to  the  chloride-of-calcium-tube  a  small  tube 
filled  with  fragments  of  moist  hydrate  of  potassa, 
through  which  the  air  is  drawn.  The  loss  of  weight 
expresses  the  amount  of  tetrafluoride  of  silicon  which 
has  been  evolved. 


85.  CRYOLITE.* 


The  analysis  may  be  made  by  means  of  concentrated 
sulphuric  acid  as  in  the  case  of  fluorite.  The  fluorine 
is  determined  by  the  loss.  For  the  direct  determina- 
tion, the  mineral  is  decomposed  in  a  platinum  retort, 
'and  the  fluorine  contained  as  fluoride  of  calcium,  as 
with  fluor-spar  and  topaz.  The  excess  of  sulphuric 

*  This  remarkable  mineral  is  found  in  an  immense  deposit  80 
feet  thick  and  300  feet  long  in  Greenland  at  the  head  of  Arksut  Bay, 
jiear  Cape  Farewell.  It  is  often  associated  with  crystals  of  galena, 
spathic  iron,  copper  and  iron  pyrites,  etc. 

The  Pennsylvania  Salt  Company  introduced  to  our  country  this 
valuable  material,  and  now  prepare  from  it  caustic  soda,  carbonates 
and  other  salts  of  soda,  sulphate  of  alumina,  etc. 

One  hundred  pounds  of  cryolite  yield  44  pounds  dry  caustic 
'soda  ;  or  75  pounds  dry  carbonate  of  soda,  203  pounds  crystallized 
carbonate  soda  ;  or  119£  pounds  bicarb,  soda,  and  24  pounds 
of.  alumina. 


156  ZIRCON. 

acid  is  driven  off  by  heat  from  the  residue,  which  is 
completely  soluble  on  being  digested  in  water,  if  the 
decomposition  was  complete.  The  alumina  is  precipi- 
tated by  carbonate  of  ammonia.  The  filtered  liquid 
is  then  evaporated  to  dry  ness,  placed  in  a  platinum 
crucible  and  carefully  raised  to  a  red  heat  with  the 
precaution  that  nothing  is  thrown  out  from  the  crucible 
by  the  decomposition  of  the  sulphate  of  ammonia.  A 
small  piece  of  carbonate  of  ammonia  is  held  in  the 
crucible  and  allowed  to  evaporate  slowly.  The  residue 
is  weighed  as  neutral  sulphate  of  soda. 


86.  ZIRCON. 
Zr02,  Si02. 

A  carefully-selected  specimen  of  zircon  which  has 
been  ignited,  and  thus  deprived  of  color,  is  levigated 
to  a  very  fine  powder,  and  fused,  at  a  good  heat,  in  a 
platinum  crucible,  with  4  parts  of  anhydrous  carbonate 
of  soda.  The  mass  is  digested  with  water,  which  dis- 
solves the  silicate  of  soda,  and  leaves  a  silicate  of  soda 
and  zirconia  as  a  crystalline  powder;  this  is  washed 
and  decomposed  by  digestion  with  concentrated  hydro- 
chloric acid.  The  mass  is  dried  up  in  a  water-bath, 
treated  with  water  containing  hydrochloric  acid,  the 
silica  filtered  offj  and  the  zirconia  precipitated  by 
ammonia. 

If  the  zirconia  contain  any  iron,  the  precipitate  is 
digested  with  oxalic  acid,  which  dissolves  the  sesqui- 
oxide  of  iron,  leaving  oxalate  of  zirconia,  at  least  the 
greater  part,  undissolved. 

Or  the  precipitate  may  be  treated  with  sulphide 
of  ammonium,  to  convert  the  iron  into  sulphide, 
the  solution  once  more  decanted,  and  the  black 
precipitate  treated  with  solution  of  sulphurous  acid, 


Z1ECON.  157 

which  immediately  dissolves  the  sulphide  of  iron 
leaving  the  zirconia  colorless.  For  quantitative  anal- 
ysis the  solution  containing  zirconia  and  iron,  after 
neutralization,  is  mixed  with  hyposulphite  of  soda, 
and  heated  until  all  the  zirconia  is  precipitated  free 
from  iron.  It  is  then  ignited. 

For  the  preparation  of  zirconia  in  large  quantities, 
the  zirconia  which  has  been  heated  to  redness  and 
cooled  suddenly  by  cold  water  is  broken  up  in  an  iron 
mortar,  sifted  and  freed  from  iron  by  hydrochloric 
acid  and  the  residuum  fused  with  two  or  three  times  its 
weight  of  the  fluorhydride  of  the  fluoride  of  po- 
tassium. It  is  gently  heated  at  first  to  drive  off  the 
water  and  afterwards  when  dry  and  hard,  the 
temperature  is  raised  until  the  mass  is  completely 
fused.  It  is  then  poured  out,  coarsely  pulverized, 
and  heated  to  boiling  with  a  little  water  mixed 
with  hydrofluoric  acid.  The  solution  of  fluozirconate 
of  potassium,  which  is  very  soluble  in  hot  water 
filtered  off  from  the  fluosilicate  of  potassium,  the 
latter  being  washed  with  hot  water.  On  cooling 
the  salt  crystallizes  in  fine  prisms.  It  may  be  purified 
by  recrystallization.  Heated  with  sulphuric  acid,  it 
is  converted  into  a  double  sulphate,  which  leaves 
after  strong  ignition  pure  zirconia  mixed  with  sul- 
phate of  potassa. 

The  ignited  zirconia  is  again  rendered  soluble 
by  heating  for  a  long  time  with  concentrated  sul- 
phuric acid,  or  with  acid  fluoride  of  ammonium. 
It  is  completely  precipitated  from  a  neutral  solution,  by 
a  boiling  saturated  solution  of  sulphate  of  potassa,  as  a 
white  pulverulent  double  salt.  After  boiling  this 
precipitate  is  scarcely  soluble  in  water  or  even  in 
acids. 

The  chloride  of  zirconium,  Zr  C1Q,  can  be  prepared 
directly  from  zircon,  as  a  white  sublimate  soluble 
in  water,  if  the  very  finely  levigated  mineral  with 
14 


158  CERITE. 

several  parts  of  pure  sugar  is  ignited,  and  the  mass, 
while  hot,  introduced  into  a  tube  of  very  hard  glass,  in 

Fig.  16. 


which  it  is  heated  to  full  redness,  while  a  stream  of  dry 
chlorine  gas  is  passed  over  it.  The  chloride  of  silicon 
passes  off  as  gas,  while  the  chloride  of  zirconium  sub- 
limes in  the  cooler  part  of  the  tube. 


87.  CERITE.* 
2  (CeO,  LaO,  DiO),  Si02-f  HO. 

Cerite,  in  fine  powder,  is  treated  with  concentrated 
sulphuric  acid,  with  which  it  is  digested,  until  the 
high  temperature  produced  by  the  combination  has 
caused  it  to  form  a  dry  mass. 

Cold  water  is  then  poured  over  it,  and  the  mix- 
ture allowed  to  digest,  in  the  cold,  until  the  sulphates 
are  dissolved.  The  solution  filtered  from  the  silica, 

*  Only  to  be  found  in  one  locality — the  mine  of  Bantnas,  near 
Riddarhytta  in  Westuianland.  May  be  obtained  from  dealers  in 
Minerals,  or  from  Stockholm. 


CERITE.  159 

which  must  be  concentrated  by  evaporation  if  too 
largely  diluted  by  the  washings,  is  mixed  with  a  boil- 
ing saturated  solution  of  sulphate  of  potassa,  and 
allowed  to  cool.  Cerium,  lanthanum  and  didymium 
are  thus  precipitated  as  double  sulphates,  while  iron, 
&c.,  remain  dissolved.  The  precipitate  is  filtered 
offj  and  washed  with  a  saturated  solution  of  sulphate  of 
potassa.  Crystalline  crusts  of  sulphate  of  potassa  are 
placed  in  the  filtrate,  and  in  this  way  the  remainder  of 
the  double  salt  is  precipitated. 

The  precipitated  salt  is  dissolved  in  the  necessary 
quantity  of  boiling  water,  with  the  addition  of  some 
hydrochloric  acid,  and  the  bases  precipitated  from 
the  hot  solution  by  an  excess  of  caustic  potassa. 
(Ammonia  precipitates  basic  salts.)  Or  the  double 
salt  is  mixed  with  pure  lamp-black  and  starch 
paste,  covered  with  coarsely  pulverized  charcoal  and 
heated  to  redness  for  one  hour. 

The  sulphide  of  potassium  formed  is  completely 
washed  out  with  water,  the  sulphide  of  cerium  dis- 
solved in  nitric  acid,  evaporated  to  dryness  and  ignited. 

After  ignition,  they  appear  as  a  cinnamon-brown 
powder.  When  converted  into  sulphates  by  diges- 
tion with  concentrated  sulphuric  acid,  they  give, 
with  water,  a  yellow  solution,  from  which  sulphate 
of  potassa  precipitates  a  lemon-yellow  mixture  of 
double  salts. 

Another  method  of  obtaining  the  oxide  of  cerium  con- 
sists in  precipitating  the  original  sulphuric  solution, 
while  hot,  with  an  excess  of  hydrate  of  potassa,  wash- 
ing the  precipitate,  and  digesting  it  with  an  excess  of 
solution  of  oxalic  acid,  when  the  iron  and  lime  are 
dissolved,  and  the  oxide  of  cerium,  &o.,  left  as  white 
oxalates,  which  are  filtered  off  and  washed.  By  igni- 
tion in  air,  they  are  converted  into  the  brown  oxides. 

There  is  at  present  no  method  of  accurately  sepa- 
rating these  three  oxides  from  each  other. 


160  CERITE. 

THE  HYDRATED  PROTOXIDE  OF  CERIUM  is  colorless, 
but  oxidizes  rapidly  on  exposure  to  air,  and  becomes 
yellow.  It  is  obtained  by  igniting  the  carbonate  of 
oxalate  in  a  current  of  hydrogen,  is  bluish-gray,  and 
oxidizes  in  the  air  to  a  yellowish-white  compound  of 
oxide  and  sesquioxide,  or  by  heating  to  an  orange-red. 
It  is  insoluble  in  nitric  and  hydrochloric  acids,  but 
soluble  in  sulphuric  with  a  yellow  color. 

THE  SESQUIOXIDE  OF  CERIUM,  in  the  pure  state,  is 
yellow,  with  a  tinge  of  red ;  when  impure,  it  is  brick- 
red.  It  is  produced  when  the  hydrate  is  ignited  in 
air.  The  sesquioxide  is  soluble  only  in  hot  concen- 
trated sulphuric  acid;  the  solution  has  a  fine  yellow 
color.  The  hydrated  sesquioxide  is  dissolved,  in  quan- 
tity, with  a  yellow  color,  by  the  alkaline  bicarbonates, 
especially  by  bicarbonate  of  ammonia.  The  sesqui- 
oxide is  insoluble  in  concentrated  hydrochloric  acid, 
but  on  addition  of  alcohol,  it  is  dissolved  in  the  form 
of  protochloride. 

OXIDE  OF  LANTHANUM  is  colorless;  when  heated 
with  water,  it  is  converted  into  the  hydrate,  which  has 
an  alkaline  reaction.  It  is  dissolved  by  a  hot  solution 
of  chloride  of  ammonium,  with  evolution  of  ammonia. 
Its  salts  are  colorless.  The  carbonate  is  insoluble  in 
carbonate  of  ammonia. 

OXIDE  OF  DIDYMIUM,  when  ignited,  is  brown. 
When  exposed  to  a  white  heat  it  assumes  a  dingy 
white  color,  with  a  tinge  of  green.  It  is  soluble  in 
acids;  its  salts  have  the  color  of  amethyst,  with  a  tinge 
of  blue ;  with  hydrate  of  potassa  they  yield  a  violet 
hydrate.  The  carbonate  is  insoluble  in  carbonate  of 
ammonia. 

The  ignited  brown  mixture  of  the  three  oxides  is 
dissolved  by  hydrochloric  acid,  with  evolution  of 
chlorine. 

If  the  mixed  hydrates,  precipitated  by  potassa,  be 
dissolved  in  nitric  acid,  the  solution  evaporated  to 


CERITE. 


161 


dry  ness,  and  ignited,  a  dark  brown  oxide  is  obtained, 
from  which  a  part,  at  least,  of  the  oxide  of  lanthanum 
may  be  obtained  in  a  pure  state.  For  this  purpose, 
the  finely-powdered  oxide  is  mixed  with  water,  to 
which  nitric  acid,  free  from  nitrous  acid,  is  added  in 
single  drops  with  continual  agitation,  in  proportion  as 
it  is  saturated.  From  the  filtered  solution,  at  a  boiling 
heat,  carbonate  of  ammonia  precipitates  carbonate  of 
oxide  of  lanthanum  in  shining,  crystalline  scales. 

When  the  oxides  precipitated  by  potassa  are  mixed 
with  a  concentrated  solution  of  potassa,  and  the  latter 
saturated  with  chlorine  gas,  and  frequently  agitated, 
the  cerium  is  converted  into  an  insoluble  yellow  com- 
pound of  the  sesquioxide,  while  didymium  and  lantha- 
num, together  with  some  cerium,  are  dissolved  as 
protochlorides.  The  yellow  sesquioxide  of  cerium  is 
digested  still  longer  with  chlorine-water,  filtered  oft', 
washed,  and  digested  with  dilute  potassa  to  remove 

Fig.  17. 


hypochlorous  acid ;  any  potassa  which  it  has  taken  up 
is  then  extracted  by  dilute  nitric  acid.     The  solution 

14* 


162  CERITE. 

of  the  protochlorides  (of  didymium  and  lanthanum)  is 
again  precipitated  by  potassa,  and  the  precipitate 
treated  a  second  time  with  potassa  and  chlorine-gas. 

The  oxide  of  cerium  can  be  obtained  nearly  pure  if 
the  mixed  oxides  are  first  treated  with  dilute  and  then 
with  concentrated  nitric  acid,  which  dissolves  out  the 
lanthanum  and  didymium.  The  solution  is  evapo- 
rated, the  salt  ignited,  and  the  oxide  again  treated  with 
very  dilute  nitric  acid.  The  oxide  of  cerium  remains 
undissolved. 

From  the  solution  the  didymium  and  lanthanum 
are  precipitated  by  ammonia  and  dissolved  in  sul- 
phuric acid.  If  the  dried  mixture  of  salts  is  dissolved 
in  water  until  it  is  saturated  at  5°  or  6°,  and  this  solu- 
tion heated  to  30°,  the  sulphate  of  the  oxide  of  lantha- 
num separates,  while  the  didymium  remains  in  solu- 
tion. By  repeating  the  operation  both  salts  may  be 
obtained  in  a  pure  state.  The  salt  of  lanthanum  is 
colorless,  and  that  of  didymium  dark  rose-red. 

Another  method  of  approximate  separation  is  the 
following.  The  cerite  is  decomposed  by  sulphuric 
acid,  the  mass  lixiviated,  the  solution  purified  with 
sulphuretted  hydrogen,  an  excess  of  hydrochloric  acid 
added,  and  the  cerite  oxides  precipitated  by  oxalic 
acid.  The  precipitate  is  washed  by  decantation,  dried 
and  mixed  with  half  its  weight  of  magnesia  alba  and 
so'me  water,  rubbed  together,  arid  dried  in  a  porcelain 
dish,  the  bottom  of  which  is  heated  to  dull  redness, 
and  the  heat  continued  with  constant  stirring  until  it 
lias  become  a  cinnamon-brown  powder,  which  contains 
all  the  cerium  as  oxide.  It  is  then  dissolved  in  warm 
concentrated  nitric  acid.  The  deep  brownish-red  solu- 
tion contains  a  double  salt  of  the  nitrate  of  the  oxides 
of  cerium  and  didymium  with  the  nitrates  of  the  oxide 
of  lanthanum  and  magnesia,  which  may  be  obtained 
in  deep  reddish-yellow  rhombohedral  crystals.  The 
red  solution  is  evaporated  to  a  syrupy  consistency, 


CERITE.  163 

and  a  large  excess  of  boiling  hot  water  containing 
some  nitric  acid  is  poured  over  it,  which  precipitates 
alone  the  basic  nitrate  of  the  oxide  of  cerium,  which 
is  washed  by  decantation  with  hot  water  mixed  with 
nitric  acid,  as  it  is  quite  soluble  in  pure  water.  The 
mother  liquor  and  wash  water  are  concentrated  to  a 
syrup  and  again  treated  in  the  same  manner. 

This  last  mother  liquor  usually  contains  only  lan- 
thanum, didymium  and  magnesia,  and  is  generally 
colored  violet,  which  color  is  destroyed  by  alcohol  and 
other  reducing  agents.  After  concentration,  crystals 
of  double  salts  of  these  bases  are  formed. 

The  metal  cerium  was  obtained  by  the  following 
process:  a  solution  of  the  brown  oxide  of  cerium  in 
hydrochloric  acid  was  mixed  with  an  equivalent  quan- 
tity of  chloride  of  potassium  and  of  chloride  of  ammo- 
nium, and  the  whole  evaporated  to  dry  ness.  The  mass 
was  then  transferred  to  a  platinum  crucible,  and  heated 
until  the  whole  of  the  chloride  of  ammonium  was 
volatilized  and  fusion  obtained.  The  fused  mass  was 
poured  out,  coarsely  powdered,  and  mixed,  while  still 
warm,  with  fragments  of  sodium,  and  introduced  into 
an  earthen  crucible  previously  heated  to  redness. 
When  the  contents  had  again  fused,  and  the  excess  of 
sodium  volatilized,  the  crucible  was  removed  from  the 
fire;  the  deep  gray  resulting  mass  was  filled  with  little 
metallic  globules.  In  a  second  experiment  a  large 
piece  of  sodium  was  thrown  into  a  red-hot  crucible 
containing  chloride  of  potassium,  and  then  the  coarsely 
powdered  chloride  used  as  before.  In  operating  in  this 
way.  a  larger  proportion  of  metallic  globules  was  ob- 
tained, some  of  which  weighed  from  50  to  60  mille- 
grams.  These  metallic  globules  appear  to  consist 
principally  of  cerium.  The  color  of  the  metal  is  inter- 
mediate between  the  color  of  iron  and  that  of  lead. 
The  metal  is  lustrous  when  polished,  and  malleable. 
Its  density  is  about  5.5  at  12°.  Exposed  to  the  air  it 


164  GADOL1NITE. 

loses  its  lustre,  and  becomes  slightly  blue.  It  feebly 
decomposes  water  at  100°.  Hydrochloric  acid  dis- 
solves it  with  energy ;  concentrated  nitric  acid  con- 
verts it  into  a  clear  brown  oxide ;  the  dilute  acid 
dissolves  it.  By  evaporation  a  white  salt  is  obtained, 
which  leaves,  after  calcination,  a  brown  oxide,  insolu- 
ble in  nitric  acid  and  in  dilute  sulphuric  acid.  Con- 
centrated sulphuric  acid  slowly  dissolves  this  oxide, 
forming  a  yellow  solution,  which  shows  the  reactions 
of  eerie  salts.  Hydrochloric  acid  dissolves  this  oxide 
with  disengagement  of  chlorine,  forming  a  colorless 
solution.  When  a  globule  of  cerium  is  heated  by  the 
blowpipe  to  dull  redness,  the  metal  inflames  and  burns 
vividly,  forming  brown  oxide;  but  upon  submitting  a 
globule  suddenly  to  a  very  high  temperature,  it  burns 
with  explosion,  sending  out  bluish  sparks.  Cerium 
powder  can  inflame  below  100°. 


88.  GADOLINITB.* 

YO,  CeO,  LaO,  ErO,  CaO,  MgO,  MnO;  FeO,  Fe2O3, 
AlaO,,SiOr 

The  finely-powdered  mineral,  dried  at  100°,  is  de- 
composed by  digestion,  in  a  porcelain  dish,  with  concen- 
trated hydrochloric  acid,  to  which  some  nitric  acid  has 
been  added,  to  peroxidize  the  iron ;  the  mass  is  com- 
pletely dried  up,  with  frequent  stirring,  in  a  water-bath, 
and  maintained  for  some  time  at  that  temperature. 

It  is  then  digested  with  .a  little  water  acidulated 
with  hydrochloric  acid,  the  silica  filtered  off',  washed 
with  hot  water,  thoroughly  dried,  ignited  and  weighed. 

*  This  rare  numeral  varies  in  composition  according  to  the  local- 
ity in  which  it  is  found.  All  specimens  contain  yttria,  oxides  of 
cerium,  iron  and  silica  as  the  ingredients,  many,  glucina  and 
small  quantities  of  lime,  magnesia  and  manganese. 


GABOLINTTE.  165 

The  solution  is  neutralized  by  ammonia,  chloride  of 
ammonium  added,  and  the  yttria,  together  with  oxides 
of  cerium  and  lanthanum  are  precipitated  by  oxalate 
of  ammonia.  Glucina,  oxides  of  iron  and  manganese 
remain  in  solution,  to  be  separated  afterwards. 

The  filtered  and  washed  mixture  of  the  three  oxal- 
ates  is  ignited  to  decompose  the  oxalic  acid,  the  oxides 
dissolved  in  a  very  little  hydrochloric  acid,  and  the 
solution  mixed  with  a  hot  saturated  solution  of  sul- 
phate of  potassa,  which  precipitates  the  oxides  of 
cerium  and  lanthanum  as  a  white  double  sulphate. 
After  the  lapse  of  twenty-four  hours  this  is  filtered  off, 
and  thoroughly  washed  with  a  saturated  solution*  of 
sulphate  of  potassa,  in  which  it  is  perfectly  insoluble. 
It  is  then  treated  as  in  No.  87. 

The  yttria  is  then  precipitated  from  the  filtered 
solution  by  oxalate  of  ammonia.  In  order  to  separate 
the  lime,  it  is  dissolved  in  hydrochloric  acid,  and  pre- 
cipitated by  ammonia. 

In  order  to  detect  the  presence  of  glucina  in  yttria, 
it  is  necessary,  since  the  latter  cannot  be  extracted  by 
caustic  potassa,  to  mix  the  precipitate  with  pure  sugar, 
and  to  carbonize  the  mass  in  a  platinum  crucible;  it  is 
then  ignited  in  a  stream  of  dry  chlorine-gas,  when  the 
chloride  of  glucinum  sublimes,  and  the  chloride  of 
yttrium  remains  in  the  carbonized  mass. 

The  following  method*  has  been  proposed  for  the 
separation  of  yttria  and  erbia : — 

The  precipitate  formed  by  oxalic  acid,  in  the 
solution  obtained  by  heating  gadolinite  with  hydro- 
chloric acid,  contains  the  oxalates  of  erbium  and 
yttrium,  besides  those  of  calcium,  cerium,  lanthanum, 
and  diclymiurn,  with  traces  of  oxalate  of  manganese 
and  silica.  These  oxalates  are  converted  into  nitrates ; 
the  solution  is  treated  with  sulphate  of  potassa.  with 

*  Method  Bahr  and  Buuseii. 


166  GADOLIN1TE. 

the  usual  precaution  (i,  831),  to  separate  the  cerium 
metals;  the  erbium  and  yttrium,  which  still  remain  in 
solution,  are  again  precipitated  by  oxalic  acid ;  the 
oxalates  are  ignited  ;  and  the  residual  oxides,  after  being 
carefully  freed  from  admixed  carbonate  of  potassa  by 
boiling  with  water,  are  dissolved  in  nitric  acid,  and 
again  precipitated  from  the  acid  solution  by  oxalic 
acid,  this  series  of  operations  being  repeated  till  the 
solution  of  the  mixed  earths  in  nitric  acid,  when  ex- 
amined in  the  spectral  apparatus,  no  longer  exhibits 
the  absorption-bands  characteristic  of  didymium.  The 
last  portion  of  calcium  and  magnesium  are  separated 
by  precipitating  the  acid  solution  of  the  mixed  earths 
with  ammonia,  the  calcium  and  magnesium  then  re- 
maining in  solution ;  the  precipitate  is  dissolved  in 
nitric  acid ;  and  the  solution,  now  containing  nothing 
but  erbia  and  yttria,  is  precipitated  by  oxalic  acid. 

To  separate  erbia  and  yttria,  the  oxalates  are  con- 
verted into  nitrates;  the  solution  is  evaporated  in  a 
platinum  dish,  till  the  first  bubbles  of  nitrous  acid 
make  their  appearance ;  and  the  dish  is  quickly  cooled 
by  placing  it  in  cold  water,  whereupon  the  viscid  mass 
solidifies  to  an  extremely  brittle  glass.  On  dissolving 
the  mass  in  a  quantity  of  warm  water  just  sufficient 
to  prevent  the  solution  from  becoming  turbid  on 
boiling,  nitrate  of  erbium,  still  containing  yttrium, 
separates  on  slow  cooling  in  needles,  which  must  be 
separated  from  the  mother  liquor  by  decantation  and 
quickly  rinsed  with  water  containing  about  three  per 
cent,  of  nitric  acid.  This  mother  liquor,  treated  in  a 
similar  manner,  yields  a  second  crop  of  crystals  of 
nitrate  of  erbium  containing  yttrium ;  the  mother 
liquor  of  this  yields  a  third  crop,  and  so  on,  the  pro- 
portion of  nitrate  of  yttria  in  the  successive  crops  of 
crystals  continually  increasing.  By  mixing  a  certain 
number  of  the  earlier  and  comparatively  pure  crops  of 
crystals,  and  treating  them  in  a  similar  manner,  pro- 


THORITE.  167 

ducts  are  obtained  of  still  greater  purity ;  and  by  re- 
peating this  mode  of  treatment  seve'ral  times,  nitrate 
of  erbium  is  ultimately  obtained  containing  no  appre- 
ciable quantity  of  yttrium. 

Pure  erbia  obtained  by  ignition  of  the  nitrate  or 
oxalate,  has  a  faint  rose-red  color  (not  yellow,  as  stated 
by  Mosander).  It  does  not  melt  at  the  strongest  white 
heat,  but  aggregates  to  a  spongy  mass,  glowing  with  an 
intense  green  light;  which,  when  examined  by  the 
spectroscope,  exhibits  a  continuous  spectrum  inter- 
sected by  a  number  of  bright  bands.  Solutions  of 
erbium-salts,  on  the  other  hand,  give  an  absorption- 
spectrum  exhibiting  dark  bands,  and  the  points  of 
maximum  intensity  of  the  light  bands  in  the  emis- 
sion-spectrum of  glowing  erbia  coincide  exactly  in 
position  with  the  points  of  greatest  darkness  in  the 
absorption-spectrum.  The  position  of  these  bands  is 
totally  different  from  those  in  the  emission  and  ab- 
sorption-spectra of  didymium ;  in  fact  there  is  not  a 
single  line  of  the  erbium-spectrum  which  corresponds 
with  that  of  didymium. 


89.  THORITE.* 
ThO2,Si02-f2HO. 

The  finely-powdered  mineral  gelatinizes  entirely 
with  concentrated  hydrochloric  acid.  The  solution  is 
evaporated  to  dryness,  the  silica  filtered  off,  the  filtrate 
highly  concentrated  by  evaporation,  and  mixed  with 

*  This  black,  amorphous  mineral,  from  Lovb'n,  near  Brevig  in 
Norway,  is  taken  here,  without  regard  to  its  rarity,  as  an  example 
of  a  compound  of  thoria,  in  order  to  direct  attention  to  the  detec- 
tion of  this  earth,  which  must  certainly  occur  more  frequently. 
The  orange-colored  orangite  of  Brevig  has  a  similar  composition. 


168  TRIPHYLITE. 

a  boiling  saturated  solution  of  sulphate  of  potassa. 
In  this  way  all  the  thoria,  like  the  oxides  of  the  cerium- 
class,  is  precipitated  as  a  white  pulverulent  double 
salt.  After  cooling,  this  is  filtered  off',  and  washed 
with  a  saturated  solution  of  sulphate  of  potassa.  There 
remains  in  the  solution  the  unessential  elements  of  the 
mineral,  iron,  manganese,  lirne,  magnesia,  alumina,  and 
the  alkalies.  It  is  then  dissolved  in  boiling  water  and 
the  alumina  precipitated  by  caustic  potassa. 

After  ignition,  thoria  is  white,  and  has  a  spec.  grav. 
of  9.4.  It  can  only  be  dissolved  in  hot  concentrated 
sulphuric  acid.  The  hydrate  of  thoria  is  insoluble  in 
potassa. 

Chloride  of  thorium  is  fusible,  and  may  be  sublimed. 

Sulphate  of  thoria  dissolves  but  slowly  in  water. 
When  the  solution  is  heated,  a  tissue  of  fine  crystalline 
needles  separates,  consisting  of  salt  containing  less 
water,  which  is  very  sparingly  soluble. 


90.  TRIPHYLITE. 
3  (FeO,  MnO,  MgO,  LiO)  PO5. 

Besides  the  principal  constituents  this  mineral  con- 
tains small  quantities  of  silicic  acid,  lime,  potassa,  and 
soda.  For  analysis  it  is  dissolved  in  hot  nitric  acid, 
the  silicic  acid  filtered  off,  a  few  grains  of  mercury 
dissolved  in  the  filtrate,  evaporated  to  dry  ness  on  the 
water-bath,  moistened  with  water,  and  again  evaporated 
to  drive  off  all  the  free  acid.  The  mass  is  then  lixiviated 
with  hot  water,  which  dissolves  all  the  bases,  the  phos- 
phoric acid  remaining  in  the  residue.  This  is  fused 
with  carbonate  of  soda  and  potash,  as  in  the  case  of 
apatite.  The  alkaline  phosphate  is  dissolved  in  water, 
the  oxide  of  iron  filtered  off,  and  the  phosphoric  acid 
precipitates  as  a  double  salt  of  magnesia. 


TRIPHYL1TE.  169 

The  solution  which  contains  the  bases,  is  evaporated, 
and  heated  to  a  dull  red  heat  to  drive  off  the  quick- 
silver. The  mass  is  then  treated  with  a  solution  of 
nitrate  of  ammonia  to  dissolve  the  lime  and  magnesia, 
and  the  oxides  of  iron  and  manganese  are  separated  by 
filtration,  the  latter  are  washed  and  added  to  the  first 
portion  containing  oxide  of  iron,  dissolved  in  hydro- 
chloric acid,  and  treated  as  in  No.  25. 

From  the  solution  which  contains  the  alkalies,  mag- 
nesia, and  lime,  the  latter  are  precipitated  by  adding  a 
small  excess  of  oxalate  of  ammonia,  the  liquid  filtered, 
concentrated  by  evaporation,  and  the  magnesia  pre- 
cipitated and  also  washed  by  a  mixture  of  caustic  and 
carbonate  of  ammonia.  The  filtered  solution  is  evap- 
orated to  dry  ness,  the  mass  heated  to  decompose  the 
nitrate  of  ammonia,  and  the  alkaline  nitrates  treated 
with  a  mixture  of  equal  parts  of  alcohol  and  ether,  in 
which  the  nitrate  of  lithia  dissolves.  The  mixture  of 
nitrates  of  potassa  and  soda  are  heated  with  chloride  of 
ammonium  to  convert  them  into  chloride,  and  then 
separated  by  chloride  of  platinum. 

The  lithia  may  be  separated  from  both  the  other 
alkalies  by  precipitating  as  SLiO,  PO5.  The  solution 
is  mixed  with  phosphate  of  soda,  and  evaporated  to 
dry  ness,  being  kept  slightly  alkaline,  by  the  addition 
from  time  to  time  of  pure  caustic  soda.  The  mass  is 
then  dissolved  in  the  smallest  possible  quantity  of 
water,  mixed  with  an  equal  quantity  of  ammonia, 
allowed  to  stand  for  twelve  hours,  filtered,  and  the  pre- 
cipitate carefully  washed  with  ammonia.  If  the  filtrate 
is  evaporated  to  dryness,  some  lithia-salt  separates. 

Magnesia  may  also  be  separated  from  lithia  by  add- 
ing hot  saturated  baryta-water  to  a  solution  of  the 
chlorides.  The  lithia  is  then  converted  into  a  sulphate, 
and  as  such  weighed. 

In  order  to  obtain  the  lithia,  the  coarsely-powdered 
mineral  is  dissolved  in  concentrated  hydrochloric  acid, 
15 


170  TRIPHYLITE. 

with  gradual  addition  of  nitric  acid ;  the  solution  is 
heated,  to  insure  the  conversion  of  all  protoxide  of  iron 
into  sesquioxide,  and  poured  off  from  any  extraneous 
minerals  which  generally  remain  undissolved.  It  is 
then  evaporated  completely  to  dry  ness,  being  constant- 
ly stirred  towards  the  last,  and  the  mass  heated  until 
all  free  acid  is  evaporated.  It  is  then  finely  powdered, 
boiled  out  with  water,  and  the  solution  filtered.  This 
now  contains  not  a  trace  of  iron,  which  remains  undis- 
solved as  white  phosphate,  but  only  chloride  of  lithium, 
mixed  with  the  chlorides  of  manganese,  magnesium, 
and  sodium.  In  order  to  precipitate  the  two  former, 
together  with  a  small  quantity  of  phosphoric  acid 
which  may  be  present,  the  solution  is  mixed  with  pure 
hydrate  of  lime,  and  boiled,  \yith  access  of  air  until 
all  the  hydrate  of  protoxide  of  manganese  is  con- 
verted into  the  brown  sesquioxide.  All  the  lithia  re- 
mains in  the  solution;  it  is  filtered  off,  arid  the  dis- 
solved lime  precipitated  by  a  mixture  of  carbonate  of 
ammonia  and  free  ammonia.  After  filtration,  the  solu- 
tion is  evaporated,  and  the  chloride  of  lithium  heated 
to  fusion  in  a  porcelain  crucible. 

The  chloride  of  lithium  still  contains  chloride  of 
sodium,  which  is  separated  by  digesting  the  mass  with 
a  mixture  of  alcohol  and  ether,  which  dissolves  the 
chloride  of  lithium,  and  leaves  the  chloride  of  sodium 
undissolved.  Or  the  impure  chloride  of  lithium  may 
be  converted  into  carbonate  by  dissolving  it  in  the 
smallest  possible  quantity  of  concentrated  ammonia, 
and  placing  in  the  solution,  which  should  be  kept  as 
cold  as  possible,  fragments  of  carbonate  of  ammonia. 
The  precipitated  carbonate  of  lithia  is  filtered  off  and 
washed  with  alcohol. 

Pure  chloride  of  lithium  is  easily  fusible;  it  im- 
parts to  the  flame  of  alcohol  a  dark  carmine-red  color  ; 
when  soda  is  present,  the  color  is  rather  orange-red. 


SPHENE.  171 

The  Triphylite  contains  more  than   7  per  cent,  of 
lithium  and  more  than  44  per  cent,  of  phosphoric  acid. 


91.  TITANITE  (SPHENE). 

(CaCM-Ti02)Si02. 

This  mineral,  even  in  the  state  of  very  fine  powder, 
is  only  attacked  with  difficulty,  and  at  best  incom- 
pletely, by  hydrochloric  01  sulphuric  acid. 

It  is  better  to  heat  it  in  a  platinum  capsule  with  bi- 
sulphate  of  ammonia,  gradually  raising  the  temper- 
ature, with  constant  stirring,  till  the  salt  fuses;  the 
heat  is  finally  increased  to  ignition.  A  little  dilute 
sulphuric  acid  is  then  added,  and  heat  again  applied 
until  the  acid  begins  to  volatilize.  When  the  mass  is 
perfectly  cold,  it  is  mixed  with  water,  the  silicic  acid 
filtered  off,  and  the  sulphate  of  lime  thoroughly 
washed. 

From  the  solution,  the  titanic  acid  is  precipitated  in 
the  cold,  together  with  the  small  quantity  of  sesqui- 
oxide  of  iron,  by  ammonia,  the  solution  filtered  rapidly, 
with  as  little  exposure  to  air  as  possible,  and  the  lime 
precipitated  by  oxalate  of  ammonia. 

The  titanic  acid  containing  iron  is  dissolved  in  hy- 
drochloric acid,  the  solution  diluted  and  carefully 
neutralized  as  completely  as  possible,  decomposed  by 
hyposulphite  of  soda,  and  heated  to  ebullition.  The 
titanic  acid  is  precipitated  and  ignited. 

Another  method  (in  which,  however,  the  silicic  acid 
is  determined  by  loss)  consists  in  decomposing  the 
mineral  by  concentrated  hydrofluoric  acid.  The  mass 
is  afterwards  mixed  with  concentrated  sulphuric  acid, 
heated  until  all  the  tetrafluoride  of  silicon  and  most  of 
the  sulphuric  acid  are  expelled,  mixed  once  more 
with  concentrated  sulphuric  acid,  and  heated  until  it 


172 


1VIENACCANITE. 


begins  to  evaporate.    The  whole  may  then  be  dissolved 
by  adding  a  sufficient  quantity  of  water. 


92.  MENACCANITE.     (TITANIC  IRON.*) 
(Ti,Fe)203. 

For  the  analysis  of  this  mineral,  and  for  the  pre- 
paration   of  pure   titanic  acid,  various   methods    are 
employed.     The  iron  dissolves  in  concentrated  hydro- 
Fig.  18. 


chloric  acid  but  very  slowly.     When  the  levigated 
powder  is  ignited  in  hydrogen-gas,  the  iron  is  reduced, 

*  Titanic  iron  occurs  in  considerable  quantity  at  Krageroe  in 
Norway,  also  in  fine  crystals  in  Orange  Go.,  N.  Y.  Most  varieties 
contain  magnesia  and  manganese. 


MENACCANITE.  173 

and  may  be  extracted  by  hydrochloric  acid ;  the 
reduction,  however,  requires  a  very  long  time  and  an 
intense  red  heat,  and,  after  all,  the  titanic  acid  is  not 
free  from  iron.  The  following  methods  are  more 
efficient : — 

I.  The  very  finely-powdered  mineral  is  fused  in  a 
platinum  crucible,  placed  within  an  earthen  crucible, 
with  3  parts  of  carbonate  of  potassa ;  the  fused  mass 
is  powdered,  and  dissolved  in  a  platinum  capsule,  in 
the  requisite  quantity  of  dilute  hydrofluoric  acid. 
Titano-fluoride  of  potassium  is  thus  produced,  which  is 
sparingly  soluble,  and  crystallizes  readily,  while  most 
of  the  sesquioxide  of  iron  is  separated  free  from 
titanium.  The  mixture  is  heated  to  boiling,  so  much 
water  being  added  as  is  requisite  to  dissolve  all  the 
salt,  and  filtered  while  boiling  hot ;  glass  vessels  rnay 
now  be  employed,  provided  an  unnecessary  excess  of 
hydrofluoric  acid  has  been  avoided.  On  cooling,  the 
greater  part  of  the  salt  separates  in  lustrous  crystalline 
scales.  It  is  filtered  off,  pressed,  washed  once  or  twice 
with  cold  water,  and  purified  completely  by  recrystal- 
lization  from  boiling  water. 

The  sesquioxide  of  iron  is  washed,  the  washings 
mixed  with  the  mother-liquor  from  the  salt,  and  with 
the  washings  from  the  latter,  and  the  dissolved  sesqui- 
oxide of  iron,  together  with  very  little  titanic  acid, 
precipitated  from  the  mixed  solution,  in  the  cold,  by 
dilute  ammonia.  The  precipitate  must  be  filtered  off 
immediately,  for  otherwise  the  titanic  acid  also  begins 
to  separate.  The  filtrate  is  then  heated  to  ebullition, 
when  all  the  titanic  acid  is  precipitated  as  white 
titanate  of  ammonia.  In  the  same  manner  the  titanic 
acid  may  be  obtained  from  the  crystallized  titano- 
fluoride  of  potassium  previously  separated. 

The  titanate  of  ammonia  is  easily  soluble  in  hydro- 
chloric acid,  and,  at  a  red  heat,  is  con  verted,  with  incan- 
descence, into  pure  titanic  acid. 


174  MENACCAXITE. 

II.  The  finely-powdered  mineral  is  fused  with    at 
least  6  parts  of   bisulphate  of  potassa  in  a  platinum 
crucible,   until  it  is  completely  dissolved ;  the  fused 
mass,  when  cool,  is  powdered  and  dissolved  in  cold 
water. 

This  solution  has  the  peculiarity,  when  long  boiled, 
of  depositing  the  whole  of  the  titanic  acid,  which  is 
not,  however,  quite  free  from  iron. 

In  order  to  obtain  it  perfectly  free  from  the  latter 
metal,  the  sesquioxide  of  iron  and  titanic  acid  are 
precipitated  by  ammonia,  the  clear  solution  decanted 
from  the  precipitate,  and  the  latter  treated  with  an 
excess  of  sulphide  of  ammonium,  which  converts  all 
the  iron  into  black  sulphide.  After  standing  for 
several  hours,  the  mixture  is  diluted  with  water,  the 
clear  liquor  decanted,  and  the  precipitate  washed  once 
or  twice  by  decantation. 

It  is  afterwards  mixed  with  sulphurous  acid,  when 
it  immediately  becomes  white,  since  the  sulphide  of 
iron  dissolves  in  the  form  of  dithionate  of  protoxide  of 
iron.  The  titanic  acid  is  filtered  off,  washed  and 
ignited,  a  fragment  of  carbonate  of  ammonia  being 
held  in  the  crucible  to  expel  any  sulphuric  acid. 

A  little  more  titanic  acid  separates  from  the  filtrate 
on  standing  for  some  time,  and  on  gently  heating. 
The  iron,  when  converted  into  sesquichloride  by 
chlorine,  or  by  heating  with  hydrochloric  acid  and 
chlorate  of  potassa,  may  be  precipitated  from  the 
solution  of  ammonia. 

III.  The   most  accurate    method   of  separation   of 
sesquioxide    of    iron    from    titanic    acid    consists   in 
decomposing  the   diluted   solution   from   No.  II.  by 
hyposulphite  of  soda.     The  titanic  acid  alone  is  pre- 
cipitated, which  is  then  ignited. 


RUTILE.  175 

93.  RUTILE.* 
Ti02. 

In  order  to  obtain  pure  titanic  acid  from  rutile,  the 
same  method  may  be  employed  as  for  titanic  iron ;  the 
first  process  is  especially  applicable  to  this  purpose. 

Or  the  very  finely-powdered  rutile  is  fused  in  a 
platinum  crucible  with  six  times  its  weight  of 
bisulphate  of  potassa.  The  mass  must  then  dissolve 
completely  in  cold  water.  If  the  water  is  heated  to 
ebullition  the  titanic  separates,  and  by  long  continued 
boiling  the  precipitation  is  complete.  Thus  obtained 
it  is  nearly  soluble  in  the  acids. 

Another  process  consists  in  converting  the  titanic 
acid  into  bichloride.  The  very  finely-powdered  rutile 
is  mixed  with  ignited  lamp-black  (1J  part  of  carbon 
for  5  parts  of  rutile)  and  so  much  starch-paste  as  will 
suffice  to  form  a  plastic  mass.  This  is  moulded  into 
cylinders  about  1  or  2  inches  long,  and  J  of  an  inch 
thick,  which  are  slowly  dried.  They  are  then 
thoroughly  ignited  in  a  covered  crucible,  and,  while 
hot,  before  they  have  absorbed  any  moisture,  intro- 
duced into  a  tube  of  porcelain  or  of  hard  glass.  A  stream 
of  dry  chlorine  is  passed  in  at  one  end  of  the  tube, 
while  the  other  opens  into  a  cooled  receiver  furnished 
with  an  egress-tube.  As  soon  as  the  apparatus  is  filled 
with  chlorine,  the  tube  is  heated  to  bright  redness, 
and  the  separation  carried  on  till  no  more  drops  of 
bichloride  of  titanium  distil  over.  The  carbonic 
oxide  and  excess  of  chlorine  are  passed  into  a  small 
quantity  of  alcohol,  which  absorbs  the  latter. 

The  bichloride  of  titanium,  which  has  a  brown 
color  due  to  sesquichloride  of  iron,  is  poured  into 
a  small  tubulated  retort  containing  some  mercury  or 

*  Occurs  most  abundantly  at  St.  Yrieix,  in  France,  and  may  be 
purchased  very  reasonably. 


176  COL  UM  BITE. 

bright  copper-turnings;  the  neck  of  the  retort  is 
drawn  out  to  a  point,  which  is  bent  downwards.  When 
the  bichloride  of  titanium  has  been  left  for  some  time 
in  contact  with  the  metal,  it  is  distilled  off  by  gentle 
ebullition,  and  immediately  received  in  tubes,  which 
are  afterwards  hermetically  sealed. 

In  order  to  prepare  pure  titanic  acid  from  the 
bichloride,  it  is  gradually  mixed  with  water,  avoiding 
all  rise  of  temperature,  which  would  render  the 
solution  turbid,  and  the  titanic  acid  precipitated  by 
ammonia. 

Pure  ignited  titanic  acid  is  white,  frequently  with  a 
tinge  of  yellow.  During  ignition  it  has  a  lemon- 
yellow  color.  When  exposed  to  a  very  high  degree 
of  heat  it  becomes  brownish.  It  is  then  perfectly 
insoluble  in  hydrochloric  acid.  By  long  digestion 
with  concentrated  sulphuric  acid,  it  is  dissolved. 


94.  COLUMBITE.  (NIOBITE.)* 
(FeO,MnO)(Cb05Ta05.) 

The  mineral  is  not  decomposed  by  acids.  It  is  best 
decomposed  by  fusing  it  in  the  form  of  a  levigated 
powder,  with  6  parts  of  bisulphate  of  potassa,  in  a 
platinum  crucible.  The  salt  is  first  fused  by  itself, 
allowed  to  solidify,  the  powdered  mineral  thrown  upon 
it,  and  the  two  gradually  fused  together.  The  fusion 
is  continued  until  the  mineral  has  entirely  dissolved. 

The  mass  is  afterwards  repeatedly  boiled  with 
water,  and  the  undissolved  hydrated  acids  filtered  off 
and  washed.  It  still  contians  sesquioxide  of  iron,  and 
commonly  also  a  small  quantity  of  binoxide  of  tin  and 
tungstic  acid. 

*  Sp.  gr.  =  5.4  to  6.39.  Often  contains  small  quantities  of  Sn02, 
WO,  and  CaO. 


TANTALITE.  177 

The  acids  are  now  digested  with  sulphide  of  ammo- 
nium, which  dissolves  the  two  latter  and  converts  the 
sesquioxide  of  iron  into  sulphide,  which  imparts  a 
black  color  to  the  acids.  This  may  be  effected  upon 
the  filter  itself,  if  the  stem  of  the  funnel  be  passed  air- 
tight into  a  flask ;  the  funnel  should  be  kept  as  closely 
covered  as  possible  after  the  mass  upon  the  filter  has 
been  carefully  mixed  with  sulphide  of  ammonium.* 

After  washing,  very  dilute  hydrochloric  acid  is 
allowed  to  flow  over  the  mass  upon  the  filter,  when 
the  sulphide  of  iron  is  dissolved,  and  the  acids  again 
become  white.  They  are  then  washed,  dried,  and 
ignited,  when  the  sulphuric  acid  with  which  they  are 
combined  is  volatilized,  which  may  be  effected  with 
greater  rapidity  and  certainty  if  a  fragment  of  car- 
bonate of  ammonia  be  held  in  the  closed  crucible 
during  ignition. 

The  stannic  and  tungstic  acids  may  be  separated 
with  more  certainty  by  fusing  the  columbic  and  tanta- 
lie  acids  with  three  times  their  weight  of  alkaline  car- 
bonates and  sulphur,  leached,  washed  with  sulphide  of 
ammonium,  and  treated  as  above. 


95.  TANTALITE. 
(FeO,  MnO)  TaO5. 

The  analysis  is  made  in  the  same  manner  as  that  of 
columbite. 

The  tanlalic  acid,  Ta05,  is  white,  even  at  a  red  heat, 
sp.  gr.  7.9.  Heated  to  redness  it  becomes  insoluble 
in  concentrated  hydrochloric  and  sulphuric  acids. 
Fused  with  caustic  potassa  or  soda,  it  behaves  like 
niobic  acid.  The  soda-salt  may  be  crystallized.  In  a 

*  Tin  and  tungsten  may  be  precipitated  by  dilute  sulphuric  acid 
as  sulphides,  which  are  converted  in  oxides  by  roasting.  If  the 
mass  is  ignited  in  hydrogen,  the  reduced  zinc  maybe  extracted  by 
concentrated  hydrochloric  acid. 


178  WOLFRAMITE. 

solution  of  this  salt  it  may  be  precipitated  by  ackls; 
for  example,  sulphuric.  If  precipitated  by  hydro- 
chloric acid,  it  is  soluble  in  an  excess,  although  not 
wholly.  With  zinc  it  gives  a  pale  blue  color,  which 
becomes  very  bright  if  the  solution  of  the  bichloride 
of  tantalum  in  sulphuric  acid  is  mixed  with  a  little 
water  and  zinc  placed  in  it.  The  blue  color  does  not 
change  to  brown.  Fused  with  salt  of  phosphorus  it 
remains  colorless  in  the  inner  flame,  and  also  when 
ignited  in  hydrogen  gas. 

The  chloride  of  tantalum,  prepared  in  the  same 
manner  as  chloride  of  columbium,  is  pure  yellow, 
easily  fused,  volatile,  forms  a  crystalline  sublimate. 
Water  transforms  it  into  hydrated  tantalic  acid  and 
hydrochloric  acid,  which  does  not  retain  it  in  so- 
lution. 

If  the  tantalic  acid  contains  titanic  acid,  by  convert- 
ing it  into  the  chloride,  a  very  fuming  liquid  bichloride 
of  titanium  is  formed.  By  fusion  with  bisulphate  of 
potassa  the  separation  is  incomplete. 


96.  WOLFRAMITE. 
(MnO,  FeO),  WO3. 

I.  In  order  to  effect  merely  a  qualitative  separation, 
for  obtaining  tungstic  acid,  the  very  finely-powdered 
mineral  is  digested  with  a  mixture  of  concentrated 
hydrochloric  acid  and  about  J  of  nitric  acid,  until  it  is 
converted  into  yellow,  pulverulent  tungstic  acid.  This 
is  filtered  oftj  washed,  dissolved  in  ammonia,*  the  solu- 

*  By  this  treatment,  there  is  left  undissolved,  besides  the  unde- 
composed  particles  of  mineral  which  have  not  been  finely  powered, 
a  white  substance,  consisting  of  silica  and  niobic  acid,  of  which 
latter  the  wolfram  contains  about  2  per  cent.  In  order  to  remove 
the  silica,  it  is  repeatedly  evaporated  with  hydrofluoric  and  sul- 
phuric acids,  then  fused  with  bisulphate  of  potassa  and  farther 
treated  as  directed  for  columbite. 


WOLFRAMITE.  179 

tion  filtered,  and  evaporated  to  crystallization.  On 
igniting  the  salt  in  the  air,  pure  yellow  tungstic  acid  is 
left. 

Or  3  parts  of  the  mineral,  very  finely  powdered,  may 
be  mixed  with  an  equal  quantity  of  carbonate  of 
potassa,  or  f  dry  carbonate  of  soda,  the  mixture 
heated  to  redness  for  half  an  hour,  and  the  tungstate 
of  potassa  which  is  formed,  may  be  extracted  from 
the  cooled  mass  with  water.* 

Pure  tungstic  acid  may  be  obtained  from  this 
solution  by  boiling,  and  adding  drop  by  drop  hydro- 
chloric acid  or  nitric  acid,  not  too  dilute,  until  there  is 
a  small  excess.  From  the  solution  neutralized  with 
hydrochloric  acid,  tungstate  of  lime  may  be  pre- 
cipitated by  chloride  of  calcium  which  may  be  decom- 
posed, after  washing,  by  boiling  hydrochloric  acid. 

If  very  finely-powdered  tungsten,  with  an  excess 
of  chloride  of  calcium,  is  kept  in  a  state  of  fusion  for 
some  time,  and  the  cooled  mass  dissolved  in  water, 
small  brilliant  octahedral  crystals  of  tungstate  of  lime 
are  obtained. 

If  tungstic  acid  is  gently  ignited  in  a  stream-  of 
hydrogen,  a  blue  tungstate  of  the  oxide  of  tungsten  is 
formed,  with  a  stronger  heat,  brown  oxide,  and  a  still 
higher  temperature,  metallic  tungsten  ^as  a  gray 
crystalline  powder. 

II.  For  quantitative  analysis,  the  levigated  mineral 
is  digested  with  a  mixture  of  4  parts  of  concentrated 
hydrochloric  acid  and  1  part  of  nitric  acid,  until  it  is 
completely  decomposed;  the  solution  is  then  evapo- 
rated to  dryness,  which  operation  should  be  finished  on 
the  water-bath,  the  chloride  of  manganese  and  sesqui- 

*  If  the  solution  is  green  from  the  presence  of  a  manganate,  it 
may  be  decomposed  by  adding  a  little  ammonia  and  warming. 
On  dissolving  the  residual  proto-sesqnioxides  of  iron  and  manga- 
nese or.  the  metallic  sulphides  obtained  as  above  mentioned  in 
concentrated  hydrochloric  acid,  columbic  acid  remains  behind. 


180  WOLFRAMITE. 

chloride  of  iron  dissolved  out,  the  tungstic  acid  filtered 
off,  washed  with  alcohol,  dissolved  in  ammonia,  sepa- 
rated by  filtration  from  the  columbic  acid,  the  solution 
evaporated,  the  residual  ammonia-salt  ignited  with  ac- 
cess of  air,  and  the  tungstic  acid  weighed. 

The  filtrate,  containing  alcohol,  is  evaporated  to 
expel  the  latter,  diluted  with  water,  and  the  oxides  of 
manganese  and  iron  separate  as  in  No.  25.  They 
usually  contain  a  little  lime. 

Or  the  levigated  mineral  is  ignited  in  a  platinum 
crucible,  with  3  parts  of  carbonate  of  potassa,  the 
mass  dissolved  in  water,  the  residual  oxides  thoroughly 
washed,  the  solution  neutralized  with  nitric  acid,  and 
the  tungstic  acid  precipitated  by  nitrate  of  suboxide 
of  mercury,  the  free  nitric  acid  being  afterwards 
neutralized  with  a  few  drops  of  ammonia,  so  that  a 
black  precipitate  begins  to  appear.  The  precipitate  is 
thoroughly  washed,  a  very  dilute  solution  of  nitrate  of 
suboxide  of  mercury  being  used  at  last,  since  other- 
wise, the  precipitate  is  liable  to  pass  through  the  filter  ; 
it  is  then  dried  and  ignited,  when  pure  tungstic  acid 
is  left. 

Or  the  solution  of  alkaline  tungstates  is  neutralized 
with  nitric  acid,  the  tungstic  acid  precipitated  by 
acetate  of  lead,  with  addition  of  a  few  drops  of  ammo- 
nia. The  washed  precipitate  is  decomposed  by  diges- 
tion with  sulphide  of  ammonium,  which  dissolves  all 
the  tungsten  as  a  sulphide.  The  filtrate  from  the 
sulphide  of  lead  is  evaporated  to  dryness,  the  mass 
carefully  oxidized  with  nitric  acid,  and  again  evapo- 
rated to  dryness  and  ignited. 

The  mixture  of  the  oxides  of  iron  and  manganese  is 
dissolved  in  concentrated  hydrochloric  acid,  which 
usually  leaves  undissolved  a  small  quantity  of  tungstic, 
columbic,  and  silicic  acids.  The  two  oxides  are  then 
separated  as  in  No.  25. 


WULFENITE.  181 

97.  SCHEELITE. 
CaO,  W03. 

The  mineral,  very  finely  powdered,  is  digested  with 
concentrated  nitric  acid,  the  mass  evaporated  nearly  to 
dry  ness,  mixed  with  alcohol,  and  filtered.  The  resi- 
dual yellow  tungstic  acid  is  washed  with  alcohol, 
ignited  and  weighed.  The  alcohol  is  expelled  from 
the  solution  by  evaporation,  the  latter  neutralized  with 
ammonia,  and  the  lime  precipitated  by  oxalate  of  am- 
monia. 


98.  WULFENITE  (MOLYBDATE  OF  LEAD). 
PbO,  Mo03. 

Several  methods  are  employed  for  obtaining  the 
molybdic  acid  from  this  mineral. 

I.  In  order  to  remove  the  carbonates  of  zinc  and  of 
protoxide  of  iron,  the  finely-powdered  ore  is  treated 
for  some  time,  and   frequently  agitated,  with  dilute 
hydrochloric  acid;  it  is  afterwards  washed  by  decan- 
tation,  and  decomposed  by  boiling  concentrated  hydro- 
chloric  acid.      The   mixture   is   then   evaporated   to 
dryness,  the  residue  powdered,  and  digested  with  am- 
monia.    Insoluble  basic  chloride  of  lead  and  molybdate 
of  ammonia  are  thus  formed;  the  solution  containing 
the  latter  is  filtered  off,  and  evaporated  to  crystallization. 
The  mother-liquor  from  the  crystals,  or  even  the  entire 
solution,  may  be  mixed  with  nitric  acid,  evaporated  to 
dryness,  and  the  residue  extracted  with  water,  when 
the  mol3Tbdic  acid  is  left. 

II.  The  powdered  ore  is  fused  with  an  equal  weight 
of  dry  carbonate  of  soda,  the  fused  mass  poured  out, 
taking  care  to  separate  it  as  far  as  possible  from  the 
oxide  of  lead  which  has  settled  at  the  bottom,  and  dis- 

16 


182  WULFENITE. 

solved  in  hot  water ;  the  small  quantity  of  lead 
carried  into  solution  is  precipitated  from  the  latter, 
\vhile  hot,  by  a  mixture  of  ammonia  and  carbonate  of 
ammonia,  the  solution  filtered,  acidified  with  nitric  acid, 
evaporated  to  dryness,  the  nitrate  of  soda  extracted 
from  the  mass  with  water,  and  the  molybdic  acid  tho- 
roughly washed. 

III.  In  order  to  avoid  the  perforation  of  the  crucible, 
which  occurs  frequently  in  this  process,  the  ore  may 
be  fused  with  an  equal  weight  of  carbonized  bitartrate 
of  potassa,  when  the  lead  separates  in  the  metallic  state, 
without  any  reduction  of  molybdic  acid  taking  place. 

IV.  The  powdered  ore  is  fused  with  an  equal  weight 
of  calcined  bitartrate  of  potassa  and  as  much  sulphur; 
the  sulphomolybdate  of  potassa  thus  produced  is  dis- 
solved  in  water,   and   the   sulphide   of  molybdenum 
precipitated  from  the  solution  by  dilute  sulphuric  acid. 
When  this  precipitate  is  washed,  dried  and  ignited  in 
a  covered  crucible,  it  leaves  a  crystalline  gray  sulphide, 
from  which  molybdic  acid  may  be  prepared  by  the 
method  employed  in  treating  molybdenite. 

Also  by  heating  the  finely  pulverized  mineral  with 
caustic  soda  and  sulphur,  which  converts  the  molybdic 
acid  into  a  sulphide,  which  is  then  precipitated  by  an 
acid  as  MoS2.  There  still  remains  in  solution  some 
molybdenum  which  may  be  precipitated  by  hydro- 
sulphuric  acid. 

V.  The  finely  powdered  mineral  is  digested,  with 
constant  stirring,  with  1|  parts  of  concentrated  sulphuric 
acid,  until  it  is  perfectly   white.     The  heat  is  then 
raised  to  incipient  volatilization  of  sulphuric  acid  the 
mixture  allowed  to  cool,  and  the  blue  pasty  mass  stirred 
up  with  much  water,  in  order  to  separate  the  sulphate 
of  lead ;  the  solution  containing  the  molybdic  acid  is 
decanted,  filtered  and  evaporated  in  a  porcelain  dish 
with  addition    of    some   nitric  acid,  until  the  sulpu- 
ric  acid  begins  to  evaporate;  the  mixture  should  be 


WULFENITE. 


183 


constantly  stirred.  The  molybdic  acid  is  thus  sepa- 
rated as  a  white  precipitate;  when  the  greater  part  of 
the  sulphuric  acid  has  been  expelled,  the  mixture  is 
diluted  with  water,  the  molybdic  acid  filtered  off'  and 
well  washed,  water  containing  nitric  acid  being  used 
towards  the  end.  Some  more  molybdic  acid  may  be 
obtained  by  evaporating  the  filtrate  and  washings.  It 
is  free  from  phosphoric  acid. 

If  it  contain  any  phosphoric  acid,  its  ammoniacal 
solution,  when  acidified  with  nitric  acid,  and  heated, 
becomes  yellow  and  deposits  a  yellow  powder. 

The  molybdic  acid  may  be  obtained  from  molybdate 
of  ammonia  by  gradually  heating  the  salt,  with  free 
access  of  air. 

It  is  always  obtained  in  a  perfectly  pure  state  by 
sublimation,  for  which  purpose  it  is  heated  in  a  plati- 
num crucible,  which  is  covered  with  a  platinum  cap- 
sule kept  full  of  water. 

For  quantitative  analysis,  the  pure  crystallized 
mineral  is  finely  powdered,  completely  decomposed  by 

Fig.  19. 


digestion  with  nitric  acid,  the  mixture  neutralized  with 
ammonia,  and  digested  with  an  excess  of  sulphide  of 


181  MOLYBDENITE. 

ammonium.  The  sulphide  of  lead  which  is  thus 
formed,  is  filtered  off  from  the  dissolved  molybdate, 
washed  with  dilute  sulphide  of  ammonium,  dried  at 
100°,  and  weighed.  From  the  solution,  the  sulphide 
of  molybdenum  is  precipitated  by  dilute  nitric  acid; 
collected  upon  a  filter,  dried  at  100°,  washed,  dried, 
and  weighed.  A  weighed  portion  of  it  is  then  intro- 
duced into  a  bulb-tube  (Fig.  19),  and  heated  in  a 
stream  of  hydrogen  until  it  loses  no  more  sulphur. 
From  the  weight  of  the  residual  MoS2,  calculated  for 
the  total  amount  of  the  precipitate,  that  of  the  molyb- 
dic  acid  is  ascertained. 


99.  MOLYBDENITE. 

MoS2. 

The  mineral  in  small  fragments  is  heated  in  a  tube 
of  hard  glass,  through  which  a  very  slow  stream  of 
dry  air  is  passed,  forming  sulphurous  acid  and  molybdic 
acid,  the  latter  subliming  in  colorless  needle-shaped 
crystals. 

If  a  large  quantity  of  the  material  is  to  be  used,  it 
is  better  to  mix  the  finely  powdered  mineral  with  an 
equal  volume  of  pure  sand,  and  roast  it  at  a  red  heat, 
frequently  stirring  it  in  the  inclined  crucible,  until  the 
smell  of  sulphurous  acid  is  no  longer  perceptible,  and 
the  mass  has  become  yellow. 

The  molybdic  acid  which  has  been  formed  is  ex- 
tracted from  the  yellow  mass  thus  produced,  by  diges- 
tion with  dilute  ammonia.  The  residue,  should  it  still 
contain  sulphide  of  molybdenum,  is  then  again 
roasted. 

The  filtered  solution  is  mixed  with  one  or  two  drops 
of  sulphide  of  ammonium,  to  separate  the  copper,  the 
precipitate  filtered  off,  the  solution  evaporated  to  dry- 
ness,  the  salt  again  dissolved  in  dilute  ammonia,  the 


BROWN   IRON   ORE.  185 

solution  filtered  from  any  impurities,  and  evaporated 
to  crystallization.     (See  Molybdate  of  Lead.) 

The  molybdic  acid  may  also  be  precipitated  from 
the  solution  of  an  alkaline  molybdate  neutralized  with 
nitric  acid,  by  basic  nitrate  of  suboxide  of  mercury. 
The  yellow  precipitate  is  allowed  to  subside,  filtered 
off,  washed  with  a  dilute  solution  of  the  mercury-salt, 
dried  and  ignited.  Molybdic  acid  may  also  be  quan- 
titatively determined,  by  this  method.  The  precipitate 
is  collected  upon  a  filter  (previously  dried  at  100°  and 
weighed),  dried  at  100°,  and  a  weighed  portion  of  it 
gently  ignited  in  a  bulb-tube  (Fig.  19),  through  which 
a  stream  of  hydrogen  is  passed,  when  dark  brown 
binoxide  of  molybdenum,  MoO2,  is  left. 


100.  BROWN  IRON-ORE,  CONTAINING  VANADIUM. 

In  order  to  extract  the  vanadium,  the  quantity  of 
which  does  not  amount  even  to  1  per  cent.,  the  finely- 
powered  ore  is  intimately  mixed  with  ^  its  weight  of 
nitre,  and  exposed,  for  an  hour,  in  a  crucible,  to  a 
gentle  ignition.  When  cool,  the  mass  is  powdered  and 
boiled  with  water. 

The  filtered  solution  has  a  yellow  color,  and  con- 
tains the  vanadates,  chromates  (molybdates  ?),  arsenates, 
phosphates,  nitrites  and  silicates  of  potassa  and  alu- 
mina. 

It  is  gradually  mixed,  and  well  stirred,  with  nitric 
acid,  taking  care  that  it  may  still  remain  slightly  alka- 
line and  that  no  nitrous  acid  is  liberated,  which 
would  reduce  the  vanadic  and  chromic  acids.  The 
precipitate  of  alumina  and  silica  thus  separated  is 
filtered  off. 

The  solution  is  then  mixed  with  an  excess  of  solu- 
tion of  chloride  of  barium,  as  long  as  any  precipitate 

16* 


186  BROWN   IRON    ORE. 

is  produced.  The  precipitate,  consisting  of  the  baryta- 
salts  of  the  above-mentioned  acids,  is  filtered  off* 
washed  and  boiled  while  yet  moist,  with  dilute  sulphuric 
acid,  which  must  not  be  added  in  too  great  excess. 
The  reddish-yellow  acid  filtrate  is  neutralized  with 
ammonia,  concentrated  by  evaporation,  and  a  fragment 
of  chloride  of  ammonium  is  placed  in  it.  In  propor- 
tion as  the  solution  becomes  saturated  with  chloride  of 
ammonium,  vanadate  of  ammonia  is  deposited  as  a 
white  or  yellow  crystalline  powder,  which  is  allowed  to 
separate  completely,  filtered  oft)  and  washed  with  a 
saturated  solution  of  chloride  of  ammonium.  When 
gradually  heated  with  full  access  of  air,  it  leaves  dark 
red  vanadic  acid,  which  fuses  when  heated  more 
strongly,  and  solidifies,  on  cooling,  to  a  very  crystal- 
line mass. 

The  solution  obtained  by  lixiviating  the  mass  after 
fusion  with  nitre,  may  also  be  mixed  with  sal- ammo- 
niac, and  boiled,  in  order  to  neutralize  the  free  alkali, 
and  to  precipitate  silica  and  phosphate  of  alumina. 
This  precipitate  usually  contains  also  vanadic  acid, 
which  may  be  converted  into  sulphide  by! fusion  with 
an  equal  weight  of  carbonate  of  potassa  and  sulphur; 
the  fused  mass  is  extracted  with  water,  and  the  brown 
sulphide  of  vanadium  precipitated  from  the  filtered 
solution  by  dilute  sulphuric  acid. 

If  the  iron-ore  be  reduced  by  fusion  with  borax 
(see  Iron  Assay),  in  a  crucible  lined  with  charcoal,  a 
well-fused,  crystalline  regulus  of  iron  is  obtained, 
which  contains  vanadium,  chromium,  arsenic,  phos- 
phorus, silicon,  and  carbon. 

Moreover,  see  Ash  of  the  Kefining-hearth. 


CHROMTTE.  187 

101.  VANADINITE.  (VANADATE  OF  LEAD.) 
PbCl,  +  3(3PbO,V03). 

There  exist  some  varieties  of  this  mineral,  at 
present  very  rare,  which  contain  no  chloride  of  lead. 

This  mineral,  when  treated  with  nitric  acid,  first 
becomes  red,  then  dissolves.  If  the  solution  be  mixed 
with  ammonia,  and  afterwards  with  an  excess  of 
sulphide  of  ammonium,  sulphide  of  lead  is  precipitated, 
and  a  dark  red  solution  obtained,  from  which  acids 
precipitate  the  dark  brown  sulphide  of  vanadium.  The 
precipitate  is' roasted  in  air,  and  afterwards  converted 
into  vanadate  of  potassa  by  fusion  with  a  small 
quantity  of  nitre.  This  salt  is  dissolved  in  a  little 
water,  and  vanadate  of  ammonia  precipitated  from  the 
solution  by  sal-ammoniac.  (See  No.  100.) 

The  mineral  is  only  imperfectly  decomposed  by 
sulphuric  acid.  The  decomposition,  however,  is  com- 
plete if  it  be  fused  with  bisulphate  of  potassa.  On 
treating  the  mass  with^water,  the  lead  remains  behind 
as  sulphate,  while  vanadic  acid  is  dissolved. 

Or  the  mineral  may  be  decomposed  by  a  mixture  of 
concentrated  hydrochloric  acid  and  alcohol,  the  chloride 
of  lead  is  washed  with  alcohol,  and  the  excess  of  acid 
evaporated  from  the  blue  solution  of  chloride  of  vana- 
dium. This  solution  is  treated  with  an  excess  of 
caustic  soda,  and  the  oxide  of  vanadium  is  converted 
into  vanadic  acid  by  a  current  of  chlorine  gas. 


102.  CHROMITE.  (CHROME-IRON-ORE.) 
FeO,  Cr2O3. 

I.  For  the  mere  qualitative  separation,  the  very  fine- 
ly powdered  ore  is  fused  for  at  least  half  an  hour,  at 


188  CFTROMITE. 

a  bright  red  heat,  with  an  equal  weight  of  nitre  and 
as  much  carbonate  of  potassa;  from  the  fused  mass, 
when  cool,  the  chromate  of  potassa  which  has  been 
produced  is  extracted  with  water. 

The  residue,  consisting  of  sesquioxide  of  iron  and 
variable  quantities  of  alumina  and  magnesia,  is  dis- 
solved in  concentrated  hydrochloric  acid,  which  gen- 
erally leaves  some  undecomposed  mineral,  and  the 
three  oxides  are  then  separated  as  in  No.  81. 

The  solution  of  chromate  of  potassa  usually  contains 
a  little  alumina,  silica  and  manganic  acid,  to  precipitate 
which,  it  is  mixed  with  a  little  carbonate  of  ammonia 
and  boiled. 

In  order  to  obtain  bichromate  of  potassa  from  this 
solution,  it  is  acidified  with  nitric  acid,  concentrated  by 
evaporation,  and  the  salt  allowed  to  crystallize  out. 

The  chromic  acid  may  be  precipitated  as  chromate 
of  lead,  Vy  neutralizing  the  solution  with  acetic  acid 
and  adding  acetate  of  lead. 

To  separate  the  chromium  as  sesquioxide,  the  solu- 
tion, is  acidified  with  sulphuric  acid,  sulphurous  acid 
added  till  the  solution  has  an  emerald-green  color, 
the  sesquioxide  of  chromium  precipitated  by  ammonia, 
washed  and  ignited. 

Or  the  yellow  solution  may  be  exactly  neutralized 
with  nitric  acid,  and  the  chromic  acid  precipitated  by 
nitrate  of  suboxide  of  mercury.  When  washed,  dried 
and  ignited,  the  yellowish-red  chromate  of  suboxide  of 
mercury  leaves  a  pure  green  sesquioxide  of  chromium. 

II.  Chromite  may  also  be  quantitatively  analyzed 
by  the  above  process,  the  fusion  being  conducted  in 
a  platinum  crucible,  though  it  will  be  found  that  a 
quantity  of  ore  will  be  left  undecomposed,  varying 
according  to  the  state  of  division  to  which  it  was  re- 
duced. From  the  solution,  after  neutralization  with 
nitric  acid,  the  chromic  acid  is  best  precipitated  by 
nitrate  of  suboxide  of  mercury ;  the  precipitate  is 


CHROMATE   OF    LEAD.  189 

washed  with  a  dilute  solution  of  that  salt  and  ignited. 
The  following  method  is  more  certain. 

The  mineral,  which  should  be  powdered  as  finely  as 
possible  and  weighed,  is  fused,  in  a  platinum  crucible, 
with  four  times  its  weight  of  bisulphate  of  potassa,  care 
being  taken  that  the  mass,  which  froths  up  at  first, 
may  not  run  over  the  side  of  the  crucible.  Ultimately, 
it  is  heated  to  redness,  and  retained  in  fusion,  at  a  red 
heat,  for  a  considerable  time.  The  salts  formed  are 
sparingly  soluble  in  water  and  acids;  the  sesquioxide 
of  chromium  must  therefore  be  converted  into  alkaline 
chromates,  for  which  purpose  there  is  added  to  the 
cooled  mass,  in  the  crucible,  about  twice  its  volume  of 
a  mixture  of  equal  parts  of  nitre  and  carbonate  of  soda. 
The  mass  is  then  heated  to  complete  fusion. 

On  cooling,  the  chromate  of  potassa  is  extracted 
with  hot  water,  the  residue  of  sesquioxide  of  iron,  alu- 
mina and  magnesia,  thoroughly  washed,  dissolved  in 
concentrated  hydrochloric  acid,  and  analyzed  as  in  No. 
81. 

The  solution  of  chromate  of  potassa  is  acidified 
with  hydrochloric  acid,  heated  to  ebullition,  and  al- 
cohol added  to  the  boiling  solution  until  it  has  acquired 
an  emerald-green  color,  when  the  sesquioxide  of  chro- 
mium is  precipitated  by  ammonia,  ignited  and  weighed. 


103.  CHROMATE  OF  LEAD. 

PbO,  CrO3. 

(Chrome-yellow,  often  adulterated  with  white  clav, 
with  BaO,  S03,— CaO,  CO2,— CaO,  SO3,  or  with  PbO, 
SO,.) 

I.  Pure  chromate  of  lead  should  give  the  quantities 
of  oxide  of  lead  and  chromic  acid  calculated  from  the 
formula. 


190  CHROMATE   OF    LEAD. 

For  analysis,  it  is  digested  with  a  mixture  of  fuming 
hydrochloric  acid  and  alcohol,  when  a  green  solution 
of  sesquichloride  of  chromium  is  produced,  the  lead 
remaining  undissolved  as  a  white  chloride.  The  latter 
is  collected  upon  a  filter,  dried  at  100°,  washed  with 
alcohol,  and  dried  at  100°.  The  solution  is  diluted 
with  water,  evaporated  to  expel  the  alcohol,  and  the 
sesquioxide  of  chromium  precipitated  by  ammonia;  the 
liquid  is  heated  to  ebullition,  the  precipitate  filtered 
off,  ignited  and  weighed. 

II.  For  mere  qualitative  analysis  of  a  specimen  of 
chrome-yellow  mixed  with  the  substances  mentioned 
above,  it  is  treated  as  before,  with  alcohol  and  hydro- 
chloric acid,  as  little  as  possible  of  the  latter  being 
employed,  in  order  that  the  clay  may  remain  un- 
touched. 

From  the  solution,  the  sesquioxide  of  chromium  is 
precipitated  by  ammonia ;  it  always,  however,  carries 
down  some  lime. 

In  order  to  separate  them  accurately,  they  must  be 
precipitated  together,  from  the  hot  solution,  by  a  mix- 
ture of  ammonia  and  carbonate  of  ammonia.  After 
drying,  the  precipitate  is  fused  with  three  times  its 
weight  of  a  mixture  of  carbonate  and  nitrate  of  potassa, 
and  the  fused  mass  treated  with  water,  which  dissolves 
the  chromate  of  potassa,  and  leaves  the  carbonate  of 
lime. 

Or  the  precipitate,  while  yet  moist,  may  be  digested 
with  hypochlorite  of  soda,  which  dissolves  the  sesqui- 
oxide of  chromium,  as  chromate  of  soda,  leaving  the 
carbonate  of  lime  undissolved.  The  solution  is  then 
heated  to  ebullition,  in  order  to  decompose  any  bi- 
carbonate. 

From  the  residue,  which  may  consist  of  the  sul- 
phates of  lime,  baryta,  and  lead,  the  first  may  be 
entirely  extracted  by  washing  with  water,  or  with  a 
solution  of  common  salt  or  of  sal-ammoniac,  in  which 


CHROMATE   OF   LEAD.  191 

it  is  far  more  soluble.  In  the  solution,  either  the  sul- 
phuric acid  is  precipitated;  by  a  baryta-salt,  or  the  lime 
by  an  oxalate. 

The  sulphate  of  lead  is  extracted  from  the  residue 
by  digestion  with  tartrate  of  ammonia  containing  free 
ammonia,  and  the  lead  precipitated  from  the  solution  by 
sulphuretted  hydrogen  or  chromate  of  potassa. 

The  mixture  of  clay  and  sulphate  of  baryta  which 
remains  at  last,  is  heated  with  concentrated  sulphuric 
acid  until  the  greater  excess  of  the  latter  has  been 
expelled,  when  the  sulphate  of  alumina  is  extracted 
with  water,  and  the  alumina  precipitated  by  ammonia. 

In  order  to  extract  the  silica  from  the  residue, 
which  contains  also  sulphate  of  baryta,  it  is  boiled  in 
a  concentrated  solution  of  carbonate  of  soda,  in  which 
the  silica  is  dissolved  and  may  be  reprecipitated  by 
sal-ammoniac.  The  residue  consists  of  carbonate  of 
baryta  mixed  with  more  or  less  undecomposed  sul- 
phate of  baryta.  (See  No.  15.) 

A    good    method   of    determining  the   amount    of 

Fig.  20. 


chromic  acid  (and  therefore  of  chromate  of  lead  con- 
tained in  a  specimen  of  commercial  chrome-yellow. 


192  URANIN1TE. 

consists  in  reducing  the  chromic  acid  to  the  state  of 
sesquioxide  of  chromium  by  means  of  oxalic  acid, 
and  in  determining  the  quantity  of  carbonic  acid  pro- 
duced. 

This  may  be  effected  in  the  same  way  as  the  testing 
of  manganese-ores  in  an  apparatus  (Fig.  20)  arranged 
for  the  quantitative  determination  of  carbonic  acid,  the 
weighed  chromate  of  lead  being  mixed  with  oxalate  of 
potassa,  and  sulphuric  acid  allowed  to  flow  upon  it. 
10  parts  by  weight  of  carbonic  acid  indicate  7.6  parts  of 
chromic  acid,  or  24.5  of  pure  chromate  of  lead.  Hence, 
100  parts  of  pure  chrome-yellow  should  give  40.4  of 
carbonic  acid. 


104.  URANINITE. 

UO,U203> 

(together  with  various  extraneous  substances,  in  varia- 
ble quantities,  including  silica,  iron,  nickel,  cobalt,  zinc, 
copper,  bismuth,  lead,  manganese,  arsenic,  antimony, 
sulphur,  lime,  and  manganese ;  sometimes  also  selenium 
and  vanadium). 

PREPARATION  OF  PURE  SESQUIOXIDE  OF  URANIUM. 
— The  finely-powdered  ore  is  digested  with  moderately 
dilute  sulphuric  acid,  with  gradual  addition  of  nitric 
acid,  until  it  is  converted  into  a  white  powder,  and 
partly  dissolved.  The  greater  excess  of  sulphuric  acid 
is  then  evaporated,  the  mass  digested  with  much  water, 
and  the  cold  solution,  after  subsidence  of  the  residue, 
filtered  off. 

The  residue  consists  of  silica,  sulphate  of  lead  and 
basic  sulphate  and  arsenate  of  bismuth. 

The  solution  is  then  heated  to  about  60°,  and  sul- 
phuretted hydrogen-gas  passed  through  it,  at  this 
temperature,  for  some  time;  the  solution  is  afterwards 
allowed  to  cool  while  the  gas  is  still  passing,  and,  when 


URANIN1TE.  193 

fully  saturated,  set  aside  in  a  covered  vessel  for  twenty- 
four  hours.  The  sulphuretted  hydrogen  is  then  ex- 
pelled by  a  gentle  heat,  and  the  precipitate  filtered  oft'. 

The  precipitate  contains  arsenic,  antimony,  copper, 
and  the  rest  of  the  lead  and  bismuth. 

The  solution  is  then  heated  to  ebullition,  and  fuming 
nitric  acid  gradually  added  to  the  boiling  liquid,  until 
all  the  protoxide  of  iron  is  reconverted  into  sesquioxide, 
and  the  solution  has  acquired  a  pure  yellow  color. 
It  is  then  precipitated  by  an  excess  of  ammonia,  and 
the  yellowish-brown  precipitate  filtered  off. 

Part  of  the  nickel,  cobalt,  zinc,  lime  and  magnesia 
remain  in  solution,  but  the  remainder  is  precipitated 
together  with  the  sesquioxides  of  uranium  and  iron. 

The  washed  precipitate  is  treated  with  a  hot,  pretty 
strong  solution  of  carbonate  of  ammonia  containing 
free  ammonia,  with  which  the  precipitate  is  digested, 
at  a  moderate  heat,  until  it  has  the  appearance  of  hy- 
drated  sesquioxide  of  iron.  The  solution  of  uranium 
is  rapidly  filtered  off,  while  hot,  and  the  residue  of 
hydrated  sesquioxide  of  iron  (still  containing  uranium) 
is  washed,  the  washings  being  received  apart  fronflhe 
filtrate. 

The  solution  (which  is  yellow,  or  colored  reddish 
by  the  cobalt)  deposits  on  cooling,  if  sufficiently  con- 
centrated, crystals  of  the  pure  double  carbonate  of 
ammonia  and  sesquioxide  of  uranium,  which  may  be 
collected,  and  washed  several  times  with  cold  water. 
When  ignited,  this  salt  leaves  pure  dark  green  proto- 
sesquioxide  of  uranium. 

The  mother-liquor  is  mixed  with  the  washings  and 
sulphide  of  ammonium  carefully  added,  drop  by  drop, 
as  long  as  it  produces  a  dark  brown  precipitate,  which 
is  immediately  filtered  off. 

The  precipitate  consists  of  the  sulphides  of  cobalt, 
nickel  and  zinc. 

The  yellow  filtrate  is  then  boiled  till  the  greater  part 
17 


194  URANIN1TE. 

of  ammoniacal  salt  is  volatilized,  and  all  the  sesqui- 
oxide of  uranium  precipitated. 

The  pure  yellow  precipitate,  uranate  of  ammonia  is 
filtered  off,  and,  when  the  filtrate  begins  to  pass 
through  turbid,  washed  with  solution  of  sal-ammoniac. 

When  ignited,  it  leaves  dark  green  proto-sesqui- 
oxide  of  uranium.  By  digesting  this  with  dilute 
hydrochloric  acid,  any  lime  and  magnesia  may  be 
extracted. 

In  order  to  prepare  protoxide  of  uranium  from  the 
uranate  of  ammonia,  it  is  dissolved  in  hydrochloric 
acid,  the  solution  mixed  with  an  excess  of  pure  sal- 
ammoniac,  and  about  an  equal  quantity  of  pure  com- 
mon salt ;  it  is  then  evaporated  to  dryness,  and  the 
mass  heated  in  a  covered  crucible  until  the  sal-ammo- 
niac is  volatilized,  and  lastly,  until  the  common  salt 
fuses.  On  dissolving  it  in  water,  the  protoxide  of 
uranium  is  left  as  a  heavy  crystalline  powder.  The 
common  salt  only  serves  to  shield  the  oxide  from  the 
action  of  air. 

When  the  quantity  is  very  small,  the  uranate  of 
ammonia  is  calcined  and  the  proto-sesquioxide  is  dis- 
solved in  hydrochloric  acid  with  a  few  drops  of  nitric 
acid;  the  addition  of  chloride  of  potassium  forms  a 
substance  U2  O2  01  +  R  01.  It  is  evaporated  to  dryness 
and  the  yellow  salt  ignited  in  a  current  of  hydrogen. 

In  order  to  extract  from  the  hydrated  sesquioxide 
of  iron  the  small  quantity  of  sesquioxide  of  uranium 
which  is  chemically  combined  with  it,  it  is  dissolved  in 
the  smallest  possible  quantity  of  hydrochloric  acid, 
the  solution  neutralized  with  carbonate  of  ammonia, 
and  added,  drop  by  drop,  with  constant  stirring,  to  a 
mixture  of  carbonate  of  ammonia  and  sulphide  of 
ammonium,  when  all  the  iron  is  separated  as  sulphide, 
and  the  sesquioxide  of  uranium  remains  in  solution; 
the  latter  may  be  precipitated  by  boiling  the  filtrate. 

Or  the  sesquioxide  of  iron  may  be  reduced  in  a 


SELENIFEROUS    DEPOSIT.  195 

stream  of  hydrogen,  and  the  reduced  pyrophoric 
mass  allowed  to  fall,  immediately,  into  dilute  hydro- 
chloric acid,  which  dissolves  the  iron,  leaving  the 
uranium  a  protoxide. 

In  order  to  detect  selenium,  arsenic,  and  vanadium 
in  pitch-blende,  it  is  ignited  with  J  of  its  weight  of  a 
mixture  of  carbonate  of  soda  and  nitre.  The  sele- 
nates,  vanadates  and  arsenates  of  the  alkalies  may  then 
be  extracted  with  water. 


105.  SELENIFEROUS  DEPOSIT  FROM  SULPHURIC 
ACID  CHAMBERS. 

(Sulphate  of  lead,  selenium,  selenide  of  mercury, 
selenates  selenites,  &c.) 

The  dry  mass  is  rubbed  to  a  thin  paste  with  a  mix- 
ture of  about  equal  parts  of  sulphuric  acid  and  water, 
and  boiled  for  a  long  time,  concentrated  nitric  acid  or 
chlorate  of  potassa  being  added  at  intervals,  to  oxidize 
the  free  selenium,  until  all  the  reddish  color  has  dis- 
appeared. 

The  mixture  is  then  diluted  with  water  and  filtered. 
The  solution  contains,  besides  iron,  copper,  mercury 
and  a  little  lead,  all  the  selenium  as  selenious  and 
selenic  acids.  It  is  mixed  either  with  about  as  much 
common  salt  as  amounts  to  half  the  weight  of  the 
deposit  originally  employed,  or  with  J  of  its  volume 
crude  of  fuming  hydrochloric  acid,  and  boiled  down 
to  about  J  of  its  original  bulk.  The  hydrochloric 
acid  reduces  the  selenic  acid  to  selenious  acid. 

On  cooling,  the  solution  is  poured  off  from  any 
sulphate  of  potassa  and  common  salt  which  may  have 
been  deposited ;  these  are  washed  several  times  with 
water,  and  the  solution  saturated  with  sulphurous  acid 
gas,  evolved  from  a  mixture  of  powdered  charcoal  and 
concentrated  sulphuric  acid. 


196  SELENI FERGUS  DEPOSIT. 

The  selenium  is  thus  precipitated  of  a  fine  red  color. 
Its  separation  is  promoted  by  digestion,  and  ultimately 
by  boiling  for  a  quarter  of  an  hour,  when  it  becomes 
black,  and  collects  into  a  dense  hard  mass.  It  is  well 
washed  and  dried. 

The  filtered  liquid  is  boiled  once  more  with  hydro- 
chloric acid,  and  again  treated  with  sulphurous  acid, 
in  case  it  should  still  contain  selenium. 

The  selenium  thus  obtained  contains  still  small 
quantities  of  lead,  copper,  and  iron,  and  especially  mer- 
cury. On  distilling  it  in  a  small  retort  or  bent  tube 
closed  at  one  end,  the  first- mentioned  impurities  are 
left  behind  as  selenides. 

In  order  to  free  it  from  mercury,  the  distilled  sele- 
nium is  dissolved  in  aqua-regia,  the  greater  excess  of 
acid  evaporated,  so  that  no  nitric  acid  may  remain,  the 
solution  mixed  with  excess  of  carbonate  of  soda,  eva- 
porated to  dryness,  and  the  saline  mass  ignited  to  expel 
the  mercury. 

The  mass  is  redissolved  in  water,  the  solution  boiled 
with  hydrochloric  acid,  and  the  selenium  again  preci- 
pitated by  sulphurous  acid. 

Or  the  ignited  mass  may  be  mixed  with  about  an 
equal  weight  of  chloride  of  ammonium,  and  heated  in 
a  retort  till  the  greater  part  of  that  salt  has  sublimed, 
when  the  selenium  is  reduced,  and  remains  behind  on 
dissolving  the  saline  mass  in  water. 

The  selenium  may  also  be  at  once  extracted,  and 
obtained  free  from  mercury,  by  fusing  the  deposit, 
with  an  equal  weight  of  carbonate  of  soda  and  about 
£  of  nitre,  in  a  crucible.  When  the  mass  is  in  a  state 
of  tranquil  fusion,  it  is  poured  out,  so  as  to  leave  the 
oxide  of  lead,  as  far  as  possible,  at  the  bottom  of  the 
crucible.  It  is  then  dissolved  in  water,  the  solution 
acidulated  with  sulphuric  acid,  the  precipitated  sul- 
phate of  lead  filtered  off,  and  the  filtrate  treated,  as 
above,  with  hydrochloric  acid  and  sulphurous  acid. 


SELENIUM  SOOT.  197 

It  is  necessary  in  this  process  that  all  the  nitric  acid 
from  the  nitre  should  either  be  expelled  or  decomposed, 
for  otherwise  part  of  the  selenium  will  escape  preci- 
pitation. 

Or  the  solution  of  the  fused  saline  mass  is  saturated 
with  hydrochloric  acid,  chloride  of  ammonium  added, 
evaporated  to  dryness,  and  the  mass  heated  in  a  retort 
until  the  chloride  of  ammonium  begins  to  sublime, 
when  all  the  selenium  is  reduced. 


106.  SELENIUM  SOOT.* 
(Selenium  with  Selenides,  Coal,  Sand,  &c.) 

The  black  mass  is  moistened  with  sulphuric  acid, 
thoroughly  washed,  fully  dried  and  distilled  from  a 
porcelain  or  hard  glass  retort,  with  a  strong  heat,  until 
most  of  the  selenium  passed  over  nearly  pure. 

The  residue  consisting  of  selenides,  coal  and  other  im- 
purities, is  dissolved  in  hydrochloric  acid  with  gradual 
addition  of  nitric  acid,  and  while  hot  the  copper 
and  iron  are  precipitated  by  caustic  soda,  the  solution 
filtered,  and  the  selenium  precipitated  by  saturating 
with  sulphurous  acid,  or  reduced  by  adding  an  excess 
of  chloride  of  ammonium,  evaporating  to  dryness  and 
heating  until  the  chloride  of  ammonium  begins  to  sub- 
lime, when  the  alkaline  salt  is  washed  out.  If  the 
selenium  is  precipitated  directly  from  the  solution 
containing  copper  more  or  less  of  this  metal  is  thrown 
down. 

In  order  to  detect  and  separate  the  sulphur  in  the 
selenium,  it  is  dissolved  in  very  strong  nitric  acid,  the 

*  It  collects  in  the  chimneys  where  the  copper  ores  are  roasted 
at  Mansfeld.  It  contains  from  30  to  40  per  cent,  of  selenium 
after  it  is  washed  and  dried. 

17* 


198  CLAUSTHALTTE. 

solution  mixed  with  hydrochloric  acid,  heated  for  some 
time  to  boiling,  and  the  sulphuric  acid  precipitated  by 
chloride  of  barium.  The  excess  of  baryta  in  the  fil- 
tered solution  is  then  precipitated  by  sulphuric  acid, 
and  afterwards  the  selenium  by  sulphurous  acid. 

In  order  to  prepare  selenious  acid,  the  selenium  is 
dissolved  in  nitric  acid,  carefully  evaporated  to  dryness, 
and  the  acid  sublimed  in  a  retort. 

To  prepare  selenic  acid,  the  selenious  acid  is  satu- 
rated with  pure  carbonate  of  copper  and  chlorine  passed 
into  it  until  all  the  selenious  salt  is  dissolved.  The 
solution  is  then  again  saturated  with  carbonate  of  cop- 
per, concentrated  by  evaporation,  and  the  selenate  of 
copper  precipitated  by  alcohol,  the  chloride  of  copper 
remaining  in  solution.  The  precipitate  is  first  washed 
with  alcohol,  then  dissolved  in  water  and  the  copper 
precipitated  by  sulphuretted  hydrogen. 


107.  CLAUSTHALITE.    (SELENIDE  OF  LEAD.) 
PbSe. 

The  analysis  is  best  effected,  like  that  of  tetrahedrite 
(No.  63),  by  means  of  chlorine-gas  (Fig.  21).  After  the 
decomposition,  the  bulb  is  again  weighed,  in  order  to 
ascertain  the  amount  of  lead  present.  The  greater  part 
of  the  selenium  is  volatilized  in  the  form  of  the  solid 
chloride ;  only  a  small  quantity  of  the  liquid  chloride 
passes  over  at  first.  These  are  conducted  into  water, 
which  is  afterwards  saturated  with  chlorine,  in  order 
to  convert  all  the  selenious  acid  into  selenic  acid ;  the 
latter  is  then  precipitated  by  chloride  of  barium,  and 
the  selenium  determined  as  selenate  of  baryta;  100 
parts  of  the  latter  correspond  to  28.2  of  selenium. 


CLAUSTHALITE. 


199 


If  the  metallic  selenides  are  mixed  or  combined 
with  the  metallic  sulphides,  as,  for  example,  in  the  na- 

Fig.  21. 


tive  selenide  of  mercury  which  contains  sulphide  of 
mercury,  the  sulphuric  acid  and  selenic  acid  formed  in 
the  analysis  are  precipitated  together  by  chloride 
of  barium,  the  precipitate  ignited  and  weighed.  A 
weighed  quantity  is  then  heated  in  a  bulb-tube,  through 
which  a  stream  of  dry  hydrogen  is  passed,  when  the 
selenate  of  baryta  is  reduced,  with  great  facility,  to  the 
state  of  selenide  of  barium,  while  the  sulphate  of  baryta 
remains  unaltered.  The  selenide  of  barium  is  then  ex- 
tracted with  dilute  hydrochloric  acid. 

In  the  same  way  the  other  metallic  selenides  which 
occur  as  minerals  may  be  analyzed,  viz.,  the  selenide 
of  silver  and  lead,  the  selenide  of  cobalt  and  lead, 
and  the  selenide  of  mercury  and  lead. 

In  order  to  obtain  the  selenium  from  the  selenide  of 
lead  occurring  in  many  places  in  the  Hartz,  the  mineral 
is  powdered,  treated  with  dilute  hydrochloric  acid  to 
remove  the  calcareous  spar  and  spathic  iron-ore,  well 


200  CAST  IRON. 

washed  and  dried.  It  is  then  very  intimately  mixed 
with  an  equal  weight  of  carbonate  of  potassa  contain- 
ing charcoal  (calcined  bitartrate  of  potassa),  covered 
with  coarse  charcoal-powder  in  a  crucible,  the  cover  of 
which  is  then  luted  on,  and  exposed  for  an  hour  to  a 
moderate  red  heat.  When  cool,  the  mass,  which  contains 
all  the  selenium  as  selenide  of  potassium,  is  quickly 
powdered  in  a  warm  mortar,  thrown  on  a  filter,  and 
washed  with  well-boiled  hot  water,  as  long  as  the 
washings  are  colored ;  during  this  operation,  the  funnel 
should  always  be  kept  full  of  water,  so  that  the  mass 
may  not  come  in  contact  with  the  air. 

The  yellowish-red  solution  of  selenide  of  potassium 
begins  immediately  to  deposit  upon  its  surface  a  film 
of  selenium,  the  whole  of  which  separates,  after  some 
days,  in  the  form  of  a  thin  reddish-black  crust;  only 
a  small  quantity  remains  in  solution  in  an  oxidized 
state.  It  may  afterwards  be  precipitated  by  heating 
the  solution  with  sulphurous  and  hydrochloric  acids. 

Since  selenide  of  lead  frequently  contains  selenide 
of  silver,  the  carbonaceous  mass  remaining  after  the 
extraction  of  the  selenide  of  potassium  may  be  fused 
with  carbonate  of  potassa  and  some  nitre.  A  metallic 
button  of  argentiferous  lead  is  thus  obtained,  from 
which  the  silver  may  best  be  separated  by  cupellation. 


108.  CAST-IEON. 

For  the  detection  and  estimation  of  the  foreign  sub- 
stances, the  total  weight  of  which  does  not  usually 
exceed  5  per  cent.;  it  is  best  to  employ  separate 
portions  of  iron. 

I.  CARBON. — The  total  amount  of  carbon  may  be 
determined  by  burning  the  iron,  in  the  state  of  very 
fine  filings,  with  the  aid  of  a  slow  stream  of  pure 


CAST   IRON.  201 

oxygen,  as  in  organic  analysis;  the  carbonic  acid 
which  is  produced  being  collected  in  a  weighed  potash 
bulb  (Fig.  22). 

The  whole  amount  of  carbon  may  be  determined 
more  accurately  by  dissolving  the  iron  in  water,  with 
5  parts  of  iodine.  The  residue  is  filtered  through  as- 
bestos and  afterwards  ignited  in  a  current  of  oxygen 
gas.  Or  it  may  be  heated  in  a  proper  apparatus  with 
six  times  its  weight  of  bichromate  of  potassa  and  an 
excess  of  moderately  concentrated  sulphuric  acid, 
when  all  the  carbon  is  converted  into  carbonic  acid. 
The  iron  may  be  treated  at  once  in  a  similar  manner. 

Fig.  22. 


Another  quantity  of  the  iron-filings  is  dissolved  in 
dilute  sulphuric  acid,  when  the  combined  carbon  is 
evolved  in  combination  with  hydrogen,  while  the 
graphite  is  left  undissolved.  In  this  operation,  the 
gas  may  be  conducted  through  a  solution  of  acetate  of 
lead,  when  the  presence  of  sulphur  is  indicated  by  the 
precipitation  of  sulphide  of  lead. 

The  residue  insoluble  in  the  acid  is  well  washed, 
dried  at  200°,  and  burnt,  as  above,  in  oxygen-gas. 
From  the  amount  of  carbonic  acid,  that  of  the  graphite 
is  calculated. 

II.  SILICON. — The  residue  from  the  first  carbon- 
determination,  which  contains  all  the  silicon  in  the 
form  of  silicic  acid,  is  dissolved  in  concentrated  hydro- 


202  CAST   IRON. 

chloric  acid,  the  solution  evaporated  to  dry  ness  on  the 
water-bath,  the  mass  digested  with  dilute  hydrochloric 
acid,  and  the  silicic  acid  filtered  off. 

III.  PHOSPHORUS. — From  the  solution  filtered  from 
the   silica,   the    phosphoric   acid   is   separated   as   in 
No.  22.     If  the  iron  contain  arsenic,  it  is  obtained  as 
arsenic  acid,  together  with  the  phosphoric  acid. 

Or  a  larger  quantity  of  iron  is  dissolved  in  aqua- 
regia,  precipitated  with  ammonia,  filtered,  dried  without 
washing,  mixed  with  about  an  equal  portion  of  car- 
bonate of  soda,  heated  to  redness  for  half  an  hour,  the 
mass  completely  dissolved  in  water,  the  solution  concen- 
trated and  the  phosphoric  acid  precipitated  as  in  No.  9. 

The  amount  of  phosphorus  may  be  less  accurately 
determined  by  heating  the  fine  iron-filings  to  redness 
with  2  parts  of  nitre  and  1  part  of  carbonate  of  soda, 
extracting  the  mass  with  water,  acidifying  the  solution 
with  hydrochloric  acid,  and  adding  excess  of  ammonia 
and  sulphate  of  magnesia. 

IV.  ARSENIC. — The  presence  of  arsenic  may  be  de- 
tected by  dissolving  the  iron  in  dilute  sulphuric  acid, 
filtering  off  the  black  residue,  and  digesting  it  with 
sulphide  of  ammonium.      From  the  filtered  solution 

Fig.  23. 


dilute  sulphuric  acid  precipitates  the  pentasulphide  of 
arsenic.    The  precipitate  is  dissolved  in  aqua-regiat  the 


CAST  IRON".  203 

nitric  acid  expelled  by  evaporation,  and  the  arsenic 
reduced  in  Marsh's  apparatus. 

The  solution  of  iron  filtered  from  the  black  residue 
is  neutralized  with  carbonate  of  soda,  mixed  with  a 
few  drops  of  sesquichloride  of  iron,  and  then  with 
acetate  of  soda,  when  arseniate  of  sesquioxide  of  iron 
is  precipitated,  may  be  easily  decomposed  by  sulphide 
of  ammonium. 

For  the  quantitative  determination  of  the  arsenic, 
the  cast-iron  is  dissolved  in  hydrochloric  acid,  with 
gradual  addition  of  nitric  acid,  the  solution  filtered 
from  the  carbon,  and  heated  with  sulphurous  acid  till 
all  the  sesquichloride  of  iron  is  converted  into  pro- 
tochloride;  the  excess  of  sulphurous  acid  is  then 
expelled  by  heat,  and  the  solution  saturated  with 
sulphuretted  hydrogen,  and  allowed  to  stand  for  twenty- 
four  hours  in  a  closed  vessel ;  the  excess  of  gas  is 
afterwards  evaporated,  and  the  precipitate  filtered  off. 

V.  COPPER. — This  metal  is  contained  in  the  preci- 
pitate produced  as  above,  by  sulphuretted  hydrogen. 
After  drying,  it  is  distilled  in  a  tube,  when  sulphide 
of  copper  remains  behind.     Or  the  sulphide  of  arsenic 
may  be  dissolved  out  by  solution  of  potassa,  or  more 
completely,  by  solution  of  monosulphide  of  potassium. 

VI.  MANGANESE. — The  solution  filtered  from   the 
precipitate  produced  by  sulphuretted  hydrogen,  in  Y. 
is  heated  to  the  boiling-point,  and  the  protoxide  of  iron 
entirely  converted  into  sesquioxide  by  adding  chlorate 
of  potassa  or  hydrochlorite  of  soda.      The  oxide  of 
manganese  and  sesquioxide  of  iron  are  then  separated 
from  each  other  by  means  of  bicarbonate  of  soda,  as 
in  No.  25. 

VII.  ALUMINUM. — The  alumina  is  contained  in  the 
sesquioxide  of  iron  which  is  then  precipitated  and  may 
be  separated  from  it  as  in  No.  21. 

VIII.  MAGNESIUM  AND  CALCIUM  remain,  together 
with  the  protoxide  of  manganese,  in  the  solution  fil- 


204:  CAST  IRON. 

tered  from  the  precipitate  produced  by  bicarbonate  of 
soda.     (See  No.  25.) 

IX.  CHROMIUM  AND  VANADIUM.— A  large  quantity 
of  the  iron-filings  is  ignited  with  2  parts  of  nitre  and  1 
part  of   carbonate  of   soda,  the  mass  extracted  with 
water,  and  the  solution  treated  as  in  No.  100,  when 
phosphoric  and  arsenic  acids  may  likewise  be  sought. 
It  is  safer  to  employ  for  this  purpose  the  carbonaceous 
residue  obtained  by  dissolving  a  large  quantity  of  the 
iron  in  dilute  sulphuric  acid. 

X.  MOLYBDENUM. — Sometimes    this  metal   is    ex- 
tracted,   together    with   the   arsenic,   by    sulphide   of 
ammonium,  from  the  black  carbonaceous  residue;  in 
such  a  case,  it   is   reprecipitated,  together    with   the 
pentasulphide  of    arsenic,  an  adding  an  acid  to  the 
solution.     If  this  precipitate  be  distilled  in  a  tube,  the 
sulphide  of  molybdenum  is  left  behind. 

If  the  cast-iron  is  rich  in  molybdenum,  it  is  dis- 
solved in  aqua-regia  and  the  molybdenum  precipitated 
by  hydrosulphuric  acid,  placing  in  the  acid  solution 
at  the  same  time  a  piece  of  zinc,  which  renders  the 
precipitation  complete. 

XL  SULPHUR. — The  sulphur  may  be  determined  ap- 
proximately by  evolving  it  as  sulphuretted  hydrogen, 
as  in  No.  1,  when  the  iron  is  dissolved  in  dilute 
sulphuric  acid.  Or  it  exists  as  sulphuric  acid  in  the 
solutions  obtained  at  III.  and  VI.,  and  may  be  precipi- 
tated by  chloride  of  barium.  Or  a  large  quantity  of  iron 
may  be  dissolved  in  aqua-regia,  and  the  sulphuric 
acid  formed  may  be  precipitated  from  the  diluted  so- 
lution by  chloride  of  barium. 

XII.  NICKEL  AND  COBALT  may  be  detected  in  the 
solution  from  which  the  copper  has  been  removed  by 
sulphuretted  hydrogen.  This  solution  is  r-eoxidized, 
and  the  sesquioxide  of  iron  precipitated  by  carbonate 
of  baryta,  after  which  the  nickel  and  cobalt  are  pre- 
cipitated by  sulphide  of  ammonium. 


ASH    OF   THE    REFINING    HEARTH.  205 

For  the  detection  of  most  of  the  admixtures,  it  is 
best  to  employ  the  black  residue  which  is  left  on  dis- 
solving the  iron  in  dilute  sulphuric  acid,  and  which  can 
easily  be  prepared  in  considerable  quantity.  It  con- 
tains silicic  acid,  carbon,  carbide  of  iron,  phosphide  of 
iron,  arsenide  of  iron,  compounds  of  chromium  and 
vanadium  with  iron,  molybdenum,  &c. 

The  total  amount  of  the  carbon  (phosphorus, 
arsenic,  chromium,  &c.  ?)  in  iron  may  be  separated  by 
digesting  the  fine  iron-filings  with  a  solution  of 
chloride  of  copper,  when  all  the  uncornbined  iron  is 
dissolved,  and  copper  precipitated  in  its  stead.  When 
the  solution  has  been  poured  off,  the  precipitated  metal 
is  digested,  out  of  contact  of  air,  with  a  neutral  solution 
of  sesquichloride  of  iron  which  redissolves  the  metallic 
copper. 

When  this  residue  is  digested  with  potassa,  the 
latter  dissolves  a  newly  formed  brown  humus-like 
substance,  together  with  phosphoric  acid,  arsenic  acid, 
and  silicic  acid.  Almost  the  whole  of  the  silicic  acid 
may  be  determined  in  this  residue. 

It  is  yet  to  be  ascertained  whether  this  residue  can 
be  analyzed  by  heating  in  chlorine-gas. 


109.  ASH  OF  THE  REFINING-HEARTH. 

Crystallized=8  FeO,  Si02. 

The  analysis  of  pure  crystals  picked  out  of  the  mass 
is  simple  and  easy,  since  they  consist  essentially  only 
of  protoxide  of  iron  and  silicic  acid.  They  are  finely 
powdered,  and  treated  with  hydrochloric  acid  and  some 
concentrated  nitric  acid  until  they  are  completely  gela- 
tinized, the  analysis  being  conducted  as  in  the  case  of 
Lievrite.  The  sesquioxide  of  iron  obtained  is  calculated 
as  protoxide. 
18 


206  ASH   OF   THE   REFINING   HEARTH. 

The  quantitative  analysis  of  the  ordinary  compact 
slag  is  far  more  difficult  and -complex,  since  it  may 
contain,  in  addition  to  the  above  principal  constituents, 
small  variable  quantities  of  the  protoxides  of  copper, 
nickel,  cobalt,  and  manganese,  besides  the  oxides  of 
chromium,  molybdenum  and  vanadium,  together  with 
alumina,  potassa,  lime,  magnesia,  arsenic  and  phos- 
phoric acids. 

Several  of  these  constituents  can  only  be  discovered 
by  a  qualitative  analysis,  for  which  a  large  amount  of 
slag  is  employed.  The  process  is  conducted  as  fol- 
lows : — 

A  pound  of  the  slag,  powdered  as  finely  as  possible, 
is  intimately  mixed  with  a.i  equal  weight  of  nitre,  and 
as  much  carbonate  of  potassa,*  and  exposed  for  an  hour, 
in  a  crucible,  to  a  moderate  red  heat.  The  mass  is 
finely  powdered,  boiled  out  with  water,  the  solution 
filtered  off,  and  the  residue  washed  several  times  with 
hot  water. 

The  solution  may  contain,  besides  alkaline  carbonates 
and  nitrites,  vanadic  acid,  chromic  acid,  molybdic  acid, 
arsenic  acid,  phosphoric  acid,  silicic  acid,  and  alumina. 
A  yellow  color  indicates  the  presence  of  chromic  acid. 

It  is  now  carefully  mixed  with  nitric  acid,  so  that  it 
may  still  remain  alkaline,  and  any  silica  which  may  be 
precipitated  is  filtered  off.  A  yellow  color  at  this 
stage  of  the  process  denotes  the  presence  of  vanadic 
acid.  The  liquid  is  then  evaporated  to  crystallization, 
and  the  greater  part  of  the  alkaline  nitrate  allowed  to 
crystallize  out  in  as  cool  a  place  as  possible.  The 
mother-liquor  is  poured  off  from  the  crystals,  which 
are  washed  several  times  with  a  little  perfectly  cold 
water ;  the  washings  are  mixed  with  the  mother-liquor, 
and  acetate  of  lead  added  as  long  as  any  precipitate  is 
produced.  This  precipitate  contains  all  the  substances 

*  Perhaps  smaller  quantities  of  both  might  be  employed. 


ASH    OF   THE    REFINING    HEARTH.  207 

above  enumerated,  in  combination  with  oxide  of  lead. 
It  is  filtered  off  and  washed  once  or  twice. 

Chromic  and  vanadic  acids  cannot  be  completely 
separated  from  oxide  of  lead  by  means  of  sulphuric 
acid.  The  precipitate  is  therefore  treated,  while  still 
moist,  with  a  mixture  of  fuming  hydrochloric  acid  and 
strong  alcohol,  with  which  it  is  heated  nearly  to  ebul- 
lition, when  all  the  lead  and  silica  are  separated  in  an 
insoluble  state,  and  the  metallic  acids  are  converted 
into  green  chlorides,  and  dissolved  together  with  the 
phosphoric  and  arsenic  acids.  The  chloride  of  lead  is 
filtered  off  and  washed  with  alcohol ;  the  green  solu- 
tion is  evaporated  to  the  consistency  of  a  syrup,  mixed 
with  a  slight  excess  of  a  concentrated  solution  of  po- 
tassa,  and  chlorine  passed  into  it  until  the  metallic 
oxides  have  redissolved  in  the  form  of  acids,  imparting 
a  yellow  color  to  the  solution.*  The  liquid  is  then 
neutralized  with  ammonia,  concentrated  as  far  as  pos- 
sible by  evaporation,  allowed  to  cool,  and  a  fragment 
of  chloride  of  ammonium  placed  in  it,  so  large  as  not 
to  be  entirely  dissolved.  The  vanadic  acid  is  thus 
almost  completely  precipitated  as  an  ammonia  salt,  in 
the  form  of  a  white  or  yellow  crystalline  powder. 
After  twenty-hours  it  is  filtered  off  and  washed,  first 
with  a  saturated  solution  of  sal-ammoniac,  afterwards 
with  alcohol.  It  may  be  purified  by  dissolving  in 
boiling  water  with  the  addition  of^some  ammonia.f 

*  Phosphate  of  alumina  may  precipitate  here,  and  must  be  ana- 
lyzed separately.  (See  No.  19.) 

f  It  is  possible  that,  if  molybdenum  be  present,  a  yellow  com- 
pound of  phosphoric  acid,  molyLdic  acid  and  ammonia  might  be 
precipitated  here.  It  is  insoluble  in  hot  dilute  nitric  acid.  This 
circumstance  might  be  made  use  of  for  separating  the  molybdic 
acid  at  once  from  the  solution  after  treatment  with  chlorine.  The 
solution  would  be  mixed  with  ammonia,  and  afterwards  boiled, 
with  addition  of  nitric  acid  in  slight  excess,  when  the  compound 
would  separate  as  a  yellow  powder.  It  contains  3  per  cent,  of  phos- 
phoric acid. 


208  ASH   OF   THE   REFINING   HEARTH. 

When  dry,  it  is  very  gradually  heated  in  a  shallow 
platinum  dish  to  expel  the  ammonia,  and  the  residual 
vanadic  acid  is  fused  at  a  low  red  heat.  If  pure,  it 
solidifies,  on  cooling,  to  a  dark  brown-red,  very 
crystalline  mass. 

The  solution  filtered  from  the  vanadate  of  ammonia 
is  mixed  with  ammonia,  and  afterwards  with  a  solution 
of  chloride  of  magnesium,  which  precipitates  all  the 
phosphoric,  and  most  of  the  arsenic  acid.  After 
twenty-four  hours,  the  precipitated  double  salts  are  fil- 
tered oft',  washed  with  dilute  ammonia,  dissolved  in 
hydrochloric  acid,  the  solution  heated  to  50°,  and  the 
arsenic  precipitated  by  a  stream  of  sulphuretted  hydro- 
gen-gas. In  the  filtrate  from  the  sulphide  of  arsenic, 
the  phosphoric  acid  may  again  be  precipitated  as  a 
double  salt  by  adding  ammonia. 

The  solution  filtered  from  the  magnesia  precipitate, 
which  still  contains  the  chromic  and  molybdic  acids, 
is  saturated  with  sulphuretted  hydrogen  and  heated, 
when  all  the  chromium  is  precipitated  as  green  sesqui- 
oxide. 

From  the  solution  filtered  from  this  precipitate,  the 
molybdenum  is  precipitated  by  dilute  sulphuric  acid 
as  a  brown  sulphide  of  molybdenum,  from  which, 
when  heated  in  a  tube,  a  mixture  of  sulphur  and  sul- 
phide of  arsenic  sublimes,  while  black  lustrous  MoS2 
remains  behind. 

The  residue  of  sesquioxide  of  iron  which  is  left 
after  ignition  with  nitre  and  alkali,  and  extraction 
with  water,  is  partly  dissolved  by  digestion  with  con- 
centrated hydrochloric  acid,  and  if  sulphuretted  hydro- 
gen be  passed  through  the  solution,  the  copper  will  be 
precipitated. 

The  solution  filtered  from  the  precipitate  is  heated 
to  the  boiling-point,  and  a  sufficient  quantity  of 
chlorate  of  potassa  gradually  added,  to  convert  the 
protochloride  of  iron  into  sesquichloride.  The  small 
quantities  of  nickel,  cobalt,  and  manganese  which  are 


GLASS.  209 

present  may  be  detected  by  precipitating  the  solution 
either  with  excess  of  ammonia  or  with  carbonate  of 
lime,  when  those  metals  remain  in  solution  and  may 
be  precipitated  by  sulphide  of  ammonium. 


110.  GLASS. 

Silicates  of  CaO,  and  KO  or  NaO,  frequently  also,  of 
PbO. 

Two  analyses  are  made,  one  by  fusion  with  an 
alkaline  carbonate,  for  the  determination  of  silicic 
acid ;  the  other  by  decomposing  the  glass  with  hydro- 
fluoric acid,  in  order  to  estimate  the  alkali. 

I.  The  very  finely-powdered  glass  fused  with  three 
times   its  weight   of  carbonate   of  potassa  and  soda 
(No.  10),    the    mass   softened   in    water,  dissolved  in 
dilute  hydrochloric  acid,  evaporated  to  dryness,  redis- 
solved  in  water,  acidulated  with   hydrochloric   acid, 
the  silica  filtered  off  and  washed. 

From  the  solution,  the  small  accidental  impurities 
of  sesquioxide  of  iron,  oxide  of  manganese,  and 
alumina,  which  are  usually  contained  even  in  white 
glass,  are  precipitated  by  ammonia,  after  the  solution 
has  been  mixed  with  some  chlorine-water  to  perox- 
idize  the  protoxide  of  manganese. 

The  lime  is  afterwards  precipitated  by  oxalic  acid, 
and  the  solution  filtered  from  the  oxalate  of  lime  is 
tested  for  magnesia,  which  may,  moreover,  have  been 
precipitated  with  the  alumina. 

If  the  glass  contain  oxide  of  lead,  that  metal  is  pre- 
cipitated by  sulphuretted  hydrogen  from  the  solution 
filtered  from  the  silicic  acid. 

II.  For  the  determination  of  alkalies,  a  second  quan- 
tity of  the  very  finely-powdered  glass  is  decomposed 
by  hydrofluoric  acid,  or  by  ignition  with  carbonate  of 
baryta,  as  in  the  analysis  of  feldspar,  the  subsequent 

18* 


210  CLAY. 

process  being  also  conducted  as  in  that  analysis,  so 
that  the  other  bases  may,  if  necessary,  be  again  deter- 
mined here. 


111.  CLAY. 

3  A12O3,  4  Si02  +  6  HO,  with  variable  quantities  of 
KO,  MgO,  FeO;  MnO,  Feldspar,  Sand,  &o. 

The  water  is  determined  by  igniting  the  clay  pre- 
viously dried  at  100°. 

I.  The  clay  is  heated  with  concentrated  sulphuric 
acid,  the  greater  excess  of  acid  evaporated,  the  residue 
dissolved  in  concentrated  hydrochloric  acid,  by  the  aid 
of  heat,  and  the  silicic  acid   filtered  off.     If  the  clay 
contain  an  admixture  of  sand  or  feldspar,  the  silica  is 
dissolved  in  a  boiling  concentrated  solution  of  carbo- 
nate of  soda,  when  the  sand  and  feldspar  remain  un- 
dissolved. 

The  hydrochloric  solution  is  considerably  diluted, 
and  gradually  neutralized  with  carbonate  of  soda,  as 
in  No.  25,  so  that  sesquioxide  of  iron  and  alumina  are 
precipitated,  while  protoxide  of  manganese,  lime,  and 
magnesia,  remain  in  solution  as  bicarbonates.  The 
separation  of  alumina  and  sesquioxide  of  iron  is  then 
effected  as  in  No.  21,  that  of  the  other  bases  as  in  No. 
25. 

II.  The  clay  is  fused  with  three  times  its  weight  of 
carbonate  of  potassa  and  soda  (see  No.  10),  the  fused 
mass  dissolved  in  dilute  hydrochloric  acid,  the  solu- 
tion evaporated  to  dryness,  the  residue  dissolved  in 
water  containing  hydrochloric  acid,  and  the  solution 
filtered  off'. 

The  separation  of  the  other  bases  contained  in  the 
solution  is  then  effected  as  in  I. 

III.  For  the  determination  of  the  alkali,  a  separate 
portion  of  the  clay  is  decomposed  by  fusion  with  hy- 


LIMESTONE.  211 

drate  or  carbonate  of  baryta,  and  the  process  conducted 
as  in  No.  80,  the  baryta  and  the  other  bases  being  pre- 
cipitated from  the  solution  by  a  mixture  of  ammonia 
and  carbonate  of  ammonia;  after  gently  heating,  the 
precipitate  is  filtered  off,  the  solution  evaporated,  and 
the  residue  ignited,  when  chloride  of  potassium  and 
chloride  of  sodium  are  left.  Or  the  analysis  may  be 
made  with  a  mixture  of  hydrofluoric  acid  and  hydro- 
chloric acid. 


112.  COMMON  LIMESTONE,  HYDRAULIC  LIMESTONE, 
MARL. 

Carbonates  of  CaO,  MgO,  FeO,  MnQ,  with  Clay  con- 
taining alkali,  and  sometimes  3  CaO,  PO5. 

I.  For  the  detection  of  the  alkali,  large  fragments  of 
the  mineral,  when  it  contains  carbonate  of  lime  in  pre- 
dominating quantity,  are  placed  in  a  charcoal  fire,  and 
heated  for  half  an  hour  to  whiteness,  when  the  clay, 
which  contains  the  alkali,  is  decomposed. 

The  ignited  mass  is  carefully  freed  from  adhering 
ash,  powdered,  exhausted  with  water,  the  solution  mixed 
with  some  carbonate  of  ammonia,  evaporated,  the  pre- 
cipitated carbonate  of  lime  filtered  off,  the  solution 
acidified  with  hydrochloric  acid,  evaporated  todryness, 
and  the  residual  chloride  of  potassium  or  sodium 
heated  to  dull  redness.  If  both  salts  be  present,  they 
are  separated  by  bichloride  of  platinum. 

II.  From  a  portion  of  the  mineral  which  has  been 
dried  at  100°  and  weighed,  the  water  is  expelled  by 
ignition  in  a  glass  tube,  and  its  quantity  determined 
by  collecting  it  in  a  weighed  chloride-of-calcium  tube. 

III.  The  carbonic  acid  may  be  expelled  from  ano- 
ther portion  of  the  mineral  by  nitric  acid  in  the  appa- 
ratus employed  for  testing  potashes,  and  its  amount 
determined  directly  by  the  loss  of  weight.    (Fig.  24.) 


212      IODIDE,  BROMIDE,  AND  CHLORIDE   OF  SODIUM. 

Or  a  weighed  quantity  of  the  substance  is  fused 
with  about  four  parts,  accurately  weighed,  of  vitrified 
borax,  in  a  platinum  crucible,  when  all  the  carbonic 

Fig.  24. 


acid  is  expelled,  and  its  amount  may  be  determined 
from  the  loss  of  weight,  or  if  the  water  is  expelled  at 
the  same  time  it  must  be  taken  into  account  in  the 
calculation.  (See  No.  7.) 

IV.  Another  very  finely  powdered  portion  is  di- 
gested with  very  dilute  nitric  acid,  which  dissolves  the 
carbonates,  together  with  the  phosphate  of  lime,  leav- 
ing the  clay,  which  is  filtered  off,  ignited  and  weighed. 
It  is  then  analyzed  as  in  No.  111. 

The  separation  of  the  other  constituents  present  in 
the  solution  is  effected  as  in  No.  13. 


113.  IODIDE,  BROMIDE,  AND  CHLORIDE  OF  SODIUM. 

The  solution  is  mixed  with  nitrate  of  protoxide  of 
palladium,  when  all  the  iodine  is  precipitated  as  dark 
brown  iodide  of  palladium,  the  bromide  of  palladium 


IODIDE,  BROMIDE,  AND   CHLORIDE   OF   SODIUM.      213 

remaining  in  solution  because  chloride  of  sodium  is 
present.  After  the  lapse  of  twelve  hours,  the  precipi- 
tate is  collected  upon  a  weighed  filter,  dried  over  oil 
of  vitriol,  or  at  a  temperature  not  exceeding  80°,  and 
weighed. 

The  excess  of  palladium  in  the  filtrate  is  separated 
by  means  of  sulphuretted  hydrogen,  in  order  to  pre- 
vent the  formation  of  a  precipitate  containing  palladium 
upon  the  subsequent  addition  of  nitrate  of  silver.  The 
excess  of  sulphuretted  hydrogen  is  then  removed  from 
the  solution  by  sulphate  of  sesquioxide  of  iron,  and 
the  filtrate  mixed  with  nitrate  of  silver,  when  a  pre- 
cipitate of  chloride  and  bromide  of  silver  is  formed, 
which  is  collected,  washed,  dried,  and  fused.  A  quan- 
tity of  this  precipitate,  weighed  in  a  bulb-tube,  is  fused 
in  a  current  of  dry  chlorine  until  bromine  vapor  ceases 
to  be  evolved,  and  the  tube  changes  no  longer  in 
weight.  Before  weighing,  every  trace  of  chlorine 
must  be  removed  from  the  bulb. 

A  simpler  method  consists  in  pouring  water  over 
the  weighed  mixture  of  bromide  and  chloride  of  silver, 
adding  a  few  drops  of  hydrochloric  acid,  and  a  frag- 
ment of  zinc.  In  twenty-four  hours  the  silver  is  com- 
pletely reduced;  it  is  rubbed  to  powder,  boiled  with 
water  containing  hydrochloric  acid,  afterwards  washed 
with  pure  water,  ignited  and  weighed. 

The  difference  between  the  equivalents  of  chlorine 
and  bromine  is  to  the  equivalent  of  bromine,  as  the 
difference  between  the  amounts  of  chloride  and  bromide 
of  silver  employed,  and  the  amount  of  chloride  which 
the  reduced  silver  ought  to  yield,  is  to  the  amount  of 
bromine  present. 

Itor  example:  200  parts  of  a  mixture  of  equal 
weights  of  chloride  and  bromide  of  silver  gave,  when 
reduced,  132,73  of  silver,  which  would  yield  176.31  of 
chloride  of  silver. 

Difference  between  the  equivalents  of  chlorine  and 


214  CRUDE   COMMON   SALT. 

bromine=44.5.  Difference  obtained=23.69.  Then 
44.5  :  80=23.69  :  x  (=42.5  bromine). 

By  the  same  indirect  method,  the  amount  of  iodine 
contained  in  a  mixture  of  iodide  with  chloride  or  bro- 
mide of  sodium  may  be  determined. 

The  iodine  may  also  be  determined  in  a  mixture  of 
chloride  and  iodide  of  potassium  or  sodium,  by  adding 
a  solution  of  sulphate  of  copper  mixed  with  sulphurous 
acid,  when  the  iodine  is  precipitated  as  white  subiodide 
of  copper,  which  is  then  washed. 

This  method  is  also  applicable  for  the  approximative 
separation  of  iodine  and  bromine. 

In  order  to  detect  iodic  acid  with  nitric  acid  (in 
nitrate  of  soda),  a  little  silver  is  dissolved  in  it.  All 
the  iodine  remains  as  insoluble  iodide  of  silver. 


114.  CRUDE  COMMON  SALT. 

I.  A  weighed  quantity  of  the  moist  salt  is  dried  for 
some  time  at  about  100°,  then  heated  to  about  300°  in 
a  covered  crucible,  and  the  water  determined  from  the 
loss. 

II.  For  the  estimation  of  the  sulphuric  acid,  the  salt  is 
dissolved  in  water  (when  any  insoluble  impurities  are 
left),  the  solution  slightly  acidified  with  hydrochloric 
acid  and  precipitated  by  chloride  of  barium. 

III.  The  lirne  is  determined  in  a  larger  quantity  of 
the  salt,  by  precipitating  it  from  its  solution  by  oxalate 
of  ammonia,  and  filtering  off  the  oxalate  of  lime  when 
it  has  subsided. 

IV.  The  filtrate  is  concentrated  by  evaporation  and 
mixed  with  ammonia  and  phosphate  of  soda  to  preci- 
pitate the  magnesia;   after  the  lapse  of  twenty-four 
hours,  the  precipitate  is  filtered  off  and  washed  with 
ammonia. 


INCRUSTATIONS   FROM   SALT-PANS.  215 

V.  The  very  small  quantity  of  potassa  which  is 
usually  present,  may  be  detected  by  concentrating  the 
solution  of  a  large  quantity  of  the  salt  so  that  a  great 
part  of  the  chloride  of  sodium  may  crystallize  out ;  the 
potassium  is  then  precipitated  from  the  mother-liquor 
with  bichloride  of  platinum. 

VI.  The  bromine  may  be  detected  by  passing  chlo- 
rine  into  the   mother-liquor  obtained  from  a  large 
quantity  of  the  saline  solution,  and  agitating  the  liquid 
with  ether,  which  takes  up  the  bromine,  and  thence 
acquires  a  yellow  color.     The  bromine  may  then  be 
converted  into  bromide  of  ammonium  by  adding  am- 
monia. 

VII.  In  order  to  detect  the  iodine,  the  mother-liquor 
is  mixed  with  some  starch-paste,  and  weak  chlorine- 
water  added  drop  by  drop ;  or  the  vapor  of  bromine 
or  of  nitrous  acid  may  be  allowed  to  flow  on  to  the 
surface  of  the  mixture. 

For  the  quantitative  determination  of  iodine  and 
bromine,  see  No.  113. 


115.  INCRUSTATIONS  FROM  SALT-PANS. 

NaCI  —  NaO,  SO,,— CaO,  SO3,— MgO,  SO,,— CaO,  C02, 
MgO,C02. 

I.  A  weighed  portion  is  heated  nearly  to  redness  in 
order  to  determine  the  water. 

II.  Another  portion  is  finely  powdered  and  boiled 
with  water,  the  residual  carbonates  of  lime  and  mag- 
nesia filtered  off,  washed  with  hot  water,  and  the  two 
bases  separated  as  in  No.  12.    This  residue  sometimes 
contains  iron  and  manganese. 

III.  The  filtrate  is  mixed  with  chloride  of  ammo- 
nium, and  the  lime  precipitated  by  oxalate  of  ammo- 
nia.    (See  No.  12.)   . 


216    MINERAL  WATERS,  WELL  WATERS,  ETC. 

IV.  The  solution  filtered  from  the   precipitate   is 
mixed  with  ammonia,  and  the  magnesia  precipitated 
by  phosphate  of  soda.     (See  No.  6.) 

V.  Another  portion  of  the  incrustation  is  dissolved 
in  hot  dilute  hydrochloric  acid,  and  the  sulphuric  acid 
precipitated  by  chloride  of  barium  (No.  3). 

VI.  A  smaller  quantity  is  dissolved  in  dilute  nitric 
acid,  and  the  chlorine  precipitated  by  nitrate  of  silver 
(No.  1). 

VII.  The  sodium  and  soda  are  calculated  from  the 
loss. 

VIII.  In  order  to  detect  a  small  quantity  of  sulphate 
of  potassa,   a    large   quantity  of  the   incrustation  is 
finely  powdered,  boiled  with  an  excess  of  hydrate  of 
baryta,  the  solution  filtered  off,  the  lime  and  baryta 
precipitated  by  a  mixture  of  ammonia  and  carbonate 
of  ammonia,  the  filtrate  acidified    with   hydrochloric 
acid  and  evaporated  to  dryness ;  the  residue  is  ignited, 
dissolved  in  water,  and  the  solution  treated  with  bi- 
chloride of  platinum. 

In  this  process  also,  the  soda  which  previously 
existed  as  sulphate,  may  be  obtained  in  the  form  of 
carbonate. 


116.  MINERAL  WATERS,  WELL-WATERS,  SALINE 
SPRINGS. 

It  is  supposed  that  the  analyst  has  an  unlimited 
quantity  of  water  at  his  disposal,  so  that  separate 
portions  may  be  employed  for  the  determination  of 
most  of  the  individual  constituents.  For  the  estima- 
tion of  those  substances  which  are  present  in  large 
quantity,  small  portions  of  water  must  be  employed, 
larger  quantities  being  taken  for  such  constituents  as 
exist  in  small  proportion. 

I.  The  specific  gravity  is  first  determined,  in  order 
to  ascertain,  by  calculation,  the  weight  of  10,  50,  or 


MINERAL  WATERS,  WELL  WATERS,  ETC.    217 

100  cub.  cents,  or  grain  measures  of  water,  so  that  the 
quantities  of  water  employed  may  be  determined  by 
measure. 

II.  Carbonic  acid  and  sulphuretted  hydro  yen- gases. — 
The  apparatus  represented  by  Fig.  25  is  used  to  deter- 
mine the  quantity  of  the  air  (nitrogen  and  oxygen) 
existing  in  the  water. 

Fig.  25 


A  flask  of  the  capacity  of  2  or  3  litres  is  filled  with 
the  water  as  well  as  a  tube  suitable  to  collect  the  gases. 
When  the  apparatus  is  thus  completely  filled  with 
water,  the  extremity  of  the  bent  tube  is  fastened  under 
a  graduated  bell-glass  full  of  mercury,  and  arranged 
over  a  mercury  trough.  The  water  is  gently  heated 
until  it  boils,  and  the  air  passes  off*  with  the  stream 
and  the  quantity  is  seen  in  the  graduated  bell-jar. 

The  apparatus  just  described  gives  sufficiently  exact 
results,  when  only  the  relation  of  the  nitrogen  and 
oxygen  dissolved  in  the  water  is  to  be  determined. 
It  presents  serious  difficulties  when  carbonic  acid  is 
also  to  be  determined ;  the  water  which  is  condensed 
in  the.  tube  being  found  in  a  sufficient  quantity 
19 


218          MINERAL  WATERS,   WELL-WATERS,   ETC. 

to  dissolve  this  acid  again  in  part  or  wholly.  This 
difficulty  may  be  avoided  by  making  a  very  simple 
modification.  A  flask  of  the  capacity  from  400  to 
500  cubic  centimetres  is  used  arranged  as  before. 


Fig. 


The  apparatus  being  completely  free  from  air,  a 
caoutchouc  tube  is  placed  upon  the  end  of  the  delivery 
tube  to  pass  to  the  top  of  the  small  graduated  bell- 
glass  and  kept  there  at  a  certain  height. 

The  height  is  regulated  on  the  supposed  volume  of 
gas  that  boiling  furnishes.  It  is  at  first  gradually 
heated  so  as  to  cause  a  small  quantity  of  water  to  pass 
out  from  the  flask,  the  volume  of  which  is  accurately 
measured  and  subtracted  from  the  first  volume  taken ; 
the  delivery  tube  is  then  placed  under  the  bell-jar,  after 
which  the  temperature  is  gradually  increased  till  the 
boiling  point  is  reached.  The  bell-jar  being  nearly 


MINERAL   WATERS,    WELL-WATERS,    ETC.          219 


filled  with  gas  and  water  which  are  evolved,  the  heat 
is  instantly  removed ;  a  vacuum  results  from  this 
which  causes  the  return  of  condensed  vapor  into  the 
flask.  This  absorption  taking  place,  it  is  again  heat- 
ed. A  certain  quantity  of  gas  is  evolved  which  is 
added  to  that  which  the  bell-glass  already  contains; 
when  this  is  nearly  full,  the  lamp  is  removed  to 
determine  the  new  absorption.  This  operation  is  re- 
peated three  or  four  times  until  the  volume  of  the  gas 
remains  stationary.  The  caoutchouc  tube  is  drawn 
down  the  bell-jar  into  the  mercury  so  that  the 
upper  portion  contains  only  the  gases  which  were  in 
solution  in  the  water  with  a  very  small  quantity  of 
this  liquid,  which  may  be  greatly  diminished  by  intro- 
ducing at  the  end  of  the  operation  some  fragments  of 
fused  chloride  of  sodium.  At  length  the  gases  con- 
tained in  the  bell-glass  are  measured,  and  the  pro- 
portion of  carbonic  acid  is  determined  by  absorbing  it 
by  means  of  potassa. 

Fig.  27. 


UJ 

Sulphuretted    hydrogen. — The    water    may    contain 
sulphur  in  two  forms,  either  combined  with  hydrogen 


220         MINERAL  WATERS,   WELL  WATERS,    ETC. 

in  the  state  of  free  hydrosulphuric  acid,  or  combined 
with  an  alkaline  metal  (sulphide  of  sodium,  potas- 
sium, &c.). 

The  sulphur  of  the  hydrosulphuric  acid,  and  that  of 
the  alkaline  sulphides  are  in  general  determined  at  the 
same  time  by  a  method  depending  upon  the  decora- 
position  of  these  compounds  by  free  iodine  and  upon 
the  coloration  that  the  slightest  possible  trace  of  iodine 
in  excess  communicates  to  starch.  A  standard  solu- 
tion of  iodine  is  made  containing  1.27  grams  of  the 
iodine  to  a  litre.  1  litre  of  this  solution  precipitates 
0.16  gr.  of  sulphur,  consequently,  1  cubic  centimetre 
of  it  precipitates  0.00016  gr.  A  definite  volume  of 
sulphur  water  being  placed  in  a  flask  a  small  quantity 
of  starch  is  added  to  it;  by  means  of  a  graduated 
cylinder,  Fig.  27,  the  standard  solution  of  iodine  is 
gradually  poured  into  the  water,  shaking  the  flask ;  a 
drop  of  iodine  in  excess  colors  the  liquid  permanently 
blue. 

III.  The  total  weight  of  the  fixed  constituents  is  ascer- 
tained by  evaporating  a  measured  quantity  of  the 
water  to  dryness,  and  carefully  heating  the  residue  to 
about  200°.     Should  the  water  contain  much  chloride 
of  magnesium,  an  error  will  result  from  the  partial 
decomposition   of    that   salt,   hydrochloric   acid   and 
magnesia    being   produced ;   this   may,   however,  be 
avoided   by  dissolving  a  weighed   quantity  of    pure 
ignited   carbonate   of  soda  in  the  water  before  eva- 
porating. 

IV.  The  carbonates  of  protoxide  of  iron,  protoxide  of 
manganese,  lime  and  magnesia,  held  in  solution  by  free 
carbonic  acid,  are  precipitated  when  a  large  quantity 
of  water  is  boiled  for  an  hour  in  a  flask.     The  pre- 
cipitate is  filtered  off',  dissolved  in  hydrochloric  acid, 
the  sesquioxide  of  iron  precipitated  by  ammonia,  and 
the  protoxide  of  manganese,  lime  and  magnesia  sepa- 
rated as  in  No.  25. 


MINERAL   WATERS,   WELL-WATERS,    ETC.         221 

V.  The  silicic  acid  is  left  undissolved  on  treating 
the  residue  obtained  by  evaporation,  with  dilute  hy- 
drochloric acid.      Should  the  water  contain  carbonate 
of  soda,  it  must  be  acidulated  with  hydrochloric  acid 
previously  to  evaporation.     If   gypsum  be  present,  a 
large  quantity  of  water  must  be  employed  to  redis- 
solve  it. 

VI.  Boracic  acid  may  be  detected  by  mixing   the 
water  with  carbonate  of  soda,  concentrating  by  eva- 
poration to  a  small  bulk,  and  acidifying  with  hydro- 
chloric  acid;    if    turmeric-paper   be   dipped   in    this 
solution,  and  dried,  it  will  become  brown  if  boracic 
acid  be  present. 

VII.  The  presence  of  nitric  acid  may  be  detected 
by  adding  to  the  partially  evaporated  water  or  to  the 
residual  salts,  a  few  drops  of    water,  colored  with  a 
solution  of  sulphate  of  indigo,  and  mixed  with  some 
hydrochloric  acid,  which  has  been  boiled.    On  boiling, 
the  solution  will  be  decolorized. 

Some  other  bodies,  especially  free  chlorine,  have 
the  same  bleaching  effect. 

Or  if  the  concentrated  solution  is  mixed  with 
several  times  its  volume  of  pure  strong  sulphuric  acid, 
the  mixture  allowed  to  cool,  and  then  a  few  drops  of  a 
concentrated  solution  of  sulphate  of  protoxide  of  iron 
cautiously  added  so  that  the  fluids  do  not  mix,  a  red- 
dish purple  or  dark-brown  stratum  is  produced  ac- 
cording to  the  quantity  of  the  acid  present.  Or  the 
very  concentrated  solution  may  be  heated  with  metallic 
copper  and  concentrated  sulphuric  acid,  when  yellowish 
red  vapors  of  nitrous  acid  make  their  appearance. 
Or  the  dry  residue  may  be  mixed  with  anhydrous 
sulphate  of  copper  or  oxide  of  lead,  and  heated  in  a 
tube.  If  pieces  of  paper  moistened  with  sulphate  of 
protoxide  of  iron  are  held  in  the  tube,  they  will  be 
colored  yellow  or  brown  if  nitric  acid  is-present. 

A  very  sensitive  reaction  consists  in  mixing  the  salt 
19* 


222          MINERAL   WATERS,   WELL-WATERS,   ETC. 

with  some  starch  paste  containing  iodide  of  potassium 
and  sulphuric  acid.  A  small  piece  of  bright  zinc  is 
placed  in  the  mixture  which  reduces  the  nitric  acid 
to  nitrous,  and  gives  the  iodine  reaction. 

VIII.  The   chlorine   is   precipitated   by  nitrate   of 
silver  after  acidifying  the  water  with  nitric  acid ;  the 
precipitate  is  treated  as  in  No.  1. 

IX.  Bromine    and    iodine,    present    only   in    very 
small  quantity,  can  only  be  detected  and  estimated  in 
large   quantities   of    water,  or   in   the   mother-liquid. 
They  are   recognized   as   in  Nos.  113  and  114.     If 
the   quantity  of    iodine  present  is  very  small  a  few 
drops  of  pure  iodide  of  potassium  and  hydrochloric 
acid  are  added  to  the  water,  and  the  amyl  reaction  made. 
In  order  to  concentrate  the  bromine,  the  water  may  be 
evaporated  to  dryness,  and  all  the  bromide  of  sodium, 
with  but  little  chloride,  extracted  from  the  residue  by 
absolute  alcohol.      When  the  alcohol  has  been  evapo- 
rated or  distilled  oft)  the  residue  is  dissolved  in  water, 
and  a  small  quantity  of  nitrate  of  silver  added,  with 
constant  stirring,  so  that  only  about  \  of  the  chlorine 
may  be  precipitated  as  chloride  of  silver ;  the  precipi- 
tate which  contains  all  the  bromine  is  weighed,  and  a 
certain  portion  of  it  analyzed  as  in  No.  114. 

X.  The  sulphuric  acid  is  precipitated  by  chloride  of 
barium  from  the  water  slightly  acidified  with  hydro- 
chloric acid. 

XI.  Potassa  and  soda. — The  water  is  evaporated  to 
about  one-half,  and  mixed,  without  filtering,  with  ex- 
cess of  baryta- water ;  the  mixture  is  allowed  to  cool, 
and  carbonate  of  ammonia  added ;  in  this  way,  the  sul- 
phuric acid,  lime,  and  excess  of  baryta  are  precipitated. 
The  filtrate  is  acidified  with  hydrochloric  acid,  evapo- 
rated to  dryness,  and  the  residue,  which  is  a  mixture 
of    chloride   of    sodium,  chloride   of    potassium,  and 
chloride  of   magnesium,  is  then  cautiously  heated  to 
redness.    The  three  metals  are  separated  as  in  No.  11. 


MINERAL   WATERS,   WELL-WATERS,    ETC.          223 

XII.  Carbonate  of  soda. — The  water  is  boiled  for  a 
long  time,  the  precipitated  earthy  carbonates  filtered 
off,  and  the  filtrate  divided  into  two  equal  parts.      In 
one  of  these,  previously  acidified  slightly  with  nitric 
acid,  the  chlorine  is  determined  by  precipitation  with 
nitrate  of  silver.      The  other  portion  is  mixed  with  a 
slight  excess  of  hydrochloric  acid,  evaporated  to  dry- 
ness,  and  the  residue  heated  nearly  to  redness ;  it  is 
then  dissolved  in  water  and  precipitated  by  nitrate  of 
silver.   The  difference  between  this  amount  of  chloride 
of  silver  and  the  former,  corresponds  to  the  quantity 
of  carbonate   of  soda   which   was   contained   in  the 
water. 

XIII.  Lime. — In  the  solution  filtered  from  the  pre- 
cipitate obtained  in  IV.,  the  lime  is  precipitated  by 
oxalate  of  ammonia,  after  addition  of  ammonia.     (See 
No.  12.) 

XIV.  Magnesia. — The    solution   filtered   from  the 
lime-precipitate   is   concentrated   by  evaporation,    al- 
lowed to  cool,  mixed  with  concentrated  ammonia,  and 
the  magnesia  precipitated  by  phosphate  of  soda.     (See 
No.  6.) 

XV.  Lithia. — The  lithia  is  best  obtained  from  the 
mother-liquid  according  to  the  method  given  in  XL 
The   solution   filtered  from   the  precipitate  is  mixed 
with  phosphate  of  soda,  evaporated  to  dryness,  and  the 
residue  treated  with  a  very  small  quantity  of  water, 
when   phosphate   of    soda   and   lithia   is   left,  which 
should,  however,  be  tested  for  magnesia. 

Or  the  mother-liquor  may  be  evaporated  to  dryness 
with  excess  of  carbonate  of  soda,  the  residue  extracted 
with  hot  water,  the  filtered  solution  mixed  with  phos- 
phate of  soda  and  evaporated  to  dryness. 

XVI.  Strontia  may  be  sought  in  the  ferruginous  and 
calcareous    stalactites    and    ochreous   deposits    from 
waters  containing  carbonic  acid. 

XVII.  Phosphoric  acid. — The  foregoing  remark  ap- 


224  SOILS. 

plies  also  to  the  phosphates.  Or  a  large  quantity  of 
water  may  be  evaporated  to  a  small  bulk,  mixed  with 
ammonia,  the  precipitate  filtered  off,  dissolved  in  nitric 
acid,  and  tested  for  phosphoric  acid  with  molybdate 
of  ammonia. 

XVIII.  Arsenic  acid,  in  combination  with  lime  or 
sesquioxide  of  iron,  must  likewise  be  sought,  in  the 
stalactites  or  ochres  from  such  waters,  with  the  aid  of 
Marsh's  apparatus.     (See  Poisoning  by  Arsenic.) 

XIX.  Antimony  and  copper,  to  be  tested  for  in  the 
deposit,  by  sulphuretted  hydrogen. 

XX.  Fluorine,  also    contained    in  the    deposit    as 
fluoride  of  calcium.      Or  it  may  be  sought  in  the  pre- 
cipitate  obtained   by  ammonia   in  XVIL,  a   part   of 
which  should  be  dried  and  moistened  with  concentrated 
sulphuric  acid  in  a  platinum  crucible  covered  with  a 
glass-plate  coated  with  wax  and  marked  in  order  to 
test  for  fluorine.     (See  No.  82.) 


117.  SOILS. 

The  ordinary  constituents  of  soils,  which  differ 
much  in  different  soils,  and  are  very  variable  in  quan- 
tity, are  salts  of  chlorine,  sulphuric  acid,  phosphoric 
acid,  silicic  acid,  carbonic  acid,  nitric  acid,  with  potassa, 
soda,  ammonia,  lime,  magnesia,  alumina,  protoxide 
of  manganese  and  protoxide  of  iron,  together  with 
sand  and  organic  matters  consisting  of  the  debris  of 
plants,  and  of  the  humous  substances  produced  by 
their  decay. 

Some  of  these  constituents  are  soluble  in  water. 

Others  are  insoluble  in  water,  but  soluble  in  dilute 
acids,  as,  for  example,  the  carbonates  and  phosphates 
of  lime  and  magnesia. 

The  remainder  are  insoluble  even  in  dilute  acids; 


SOILS.  225 

these  consist  of  quartz  and  of  particles  of  feldspar, 
mica,  and  hornblende  arising  from  the  disintegration 
of  different  kinds  of  rock. 

The  soil  to  be  examined  is  collected  from  different 
parts  of  the  field,  well  powdered,  allowed  to  dry  in  the 
air,  and  uniformly  mixed. 

It  is  most  convenient  to  determine  the  greater  num- 
ber of  the  constituents  in  separate  portions  of  the  soil. 

I.  Water. — A  weighed  portion  of  air-dried  soil  is 
heated  to  100°,  and  retained  at  that  temperature  till  its 
weight  is  constant.    In  this  way  the  amount  of  hygro- 
scopic water  is  ascertained. 

In  order  to  determine  the  combined  water  in  the 
salts,  clay,  &c.,  the  soil  may  be  heated  to  200°  or  300°, 
when  the  ammonia  also  may  be  expelled. 

II.  Organic  matters. — The  dry  soil  is  ignited  with 
access  of  air,  moistened  with  carbonate  of  ammonia, 
and  again   heated  nearly  to   redness.     The   loss   in 
weight  (ammonia  and  nitric  acid  being  taken  into  ac- 
count) indicates  the  total  amount  of  organic  matter. 

The  amount  of  nitrogenized  organic  matter  can  only 
be  determined  by  ultimate  analysis,  when  the  ammonia 
and  nitric  acid  must  not  be  neglected  in  the  calcula- 
tion. 

Certain  organic  substances,  such  as  fatty  and  resinous 
matters,  may  be  extracted  from  the  dried  soil  by  hot 
alcohol  and  ether. 

The  humous  substances  may  be  extracted  by  boiling 
the  soil  with  solution  of  potassa;  they  are  separated, 
though  not  completely,  from  the  brown  filtered  solution, 
in  the  form  of  a  brown  precipitate,  on  adding  hydro- 
chloric acid. 

III.  Ammonia. — The  soil  is  distilled  with  solution 
of  soda,  and  the  ammonia  collected  and  determined  as 
in  No.  5. 

IV.  Nitric  acid. — The  analyst  must  be  satisfied  with 
the  qualitative  detection  of  nitric  acid.    The  soil  is  ex- 


226  SOILS. 

tracted  with  water,  the  filtered  solution  evaporated  to 
a  small  bulk,  and  the  reactions  made,  given  under 
nitric  acid,  No.  116. 

V.  The  constituents  soluble  in  water. — A  large  quan- 
tity of  the  air-dried  soil,  from  1000  to  2000  grammes,  is 
heated  nearly  to  ebullition,  with  water,  for  a  consider- 
able time;  the  residue  is  filtered  off  and  thoroughly 
washed  with  hot  water.  The  whole  liquid  is  evaporated 
to  about  its  original  volume,  carefully  weighed  or 
measured,  and  separate  portions  of  it,  weighed  or 
measured  off,  are  employed  for  the  determination  of 
the  following  constituents. 

a.  The  total  weight  of  the  portion  soluble  in  water 
is  ascertained  by  evaporation  to  dry  ness. 

b.  Sulphuric   acid    is    precipitated   by   chloride   of 
barium  from  the  solution  acidified  with  hydrochloric 
acid. 

c.  Chlorine  is  precipitated  by  nitrate  of  silver,  after 
acidification  with  nitric  acid. 

d.  Silicic  acid. — The  solution  is  mixed  with  hydro- 
chloric acid,  evaporated  to  dryness,  the   residue   ex- 
tracted with  dilute  hydrochloric  acid,  and  the  silica 
filtered  off. 

e.  Lime,  magnesia,  alumina,  protoxide  of  iron,  andprot- 
oxide  of  manganese  may  be  contained  in  the  filtrate  from 
d;  they  may  be  separated  as  in  No.  81. 

/.  Potassa  and  soda. — The  solution  is  mixed  with 
hydrochloric  acid,  evaporated  to  dryness,  the  residue 
dissolved  in  a  little  water,  baryta- water  added  in  excess, 
the  mixture  digested  for  some  time,  filtered  off,  and 
the  baryta  and  lime  precipitated  from  the  filtrate  by 
carbonate  of  ammonia.  The  solution  filtered  from 
these  can  contain  only  potassa  and  soda,  which  are  es- 
timated as  chlorides,  and  are  separated  as  usual. 

g.  Phosphoric  acid,  which  can  only  be  present  if  the 
solution  contain  no  lime,  &c.,  is  precipitated  as  phos- 
phate of  magnesia-ammonia. 


SOILS. 

VI.  Constituents  insoluble  in  water,  but  soluble  in 
dilute  hydrochloric  acid. — From  50  to  100  grms.  of  the 
residue  obtained  in  V.  (previously  washed,  dried, 
and  uniformly  mixed),  are  weighed  off,  mixed  with 
water,  in  a  flask,  to  a  thin  paste,  heatejd,  and  hydro- 
chloric acid  gradually  added  until  the  effervescence 
ceases ;  the  mixture  is  then  heated  for  some  time,  with 
frequent  agitation,  the  insoluble  residue  filtered  off 
and  well  washed.  The  solution  is  concentrated  by 
evaporation,  weighed  or  measured,  and  divided  into 
separate  portions  for  the  different  determinations.  If 
the  soil  contain  much  organic  matter,  it  must  be  feebly 
ignited  with  access  of  air  previously  to  the  extraction 
with  hydrochloric  acid. 

a.  Silicic  acid. — The  solution  is  evaporated  to  dry- 
ness  with  addition  of  some  nitric  acid. 

b.  Sulphuric  acid. — From  a  weighed  portion  of  the 
acid   solution,  filtered  from  the  silica,  the   sulphuric 
acid  is  precipitated  by  chloride  of  barium. 

c.  Alkalies. — Another   portion   of    this  solution   is 
treated  as  in  V.,/,  with  baryta- water. 

d.  Phosphoric  acid,  lime,  magnesia,  alumina,  protoxide 
of  manganese,  and  protoxide  of  iron,  are  separated  and 
determined   in   the   greater   portion   of    the   solution 
filtered  from  the  silica;  according  to  the  method  given 
in  No.  26. 

e.  The  carbonic  acid,  may  be  determined  in  a  separate 
portion  of  the  washed  soil,  as  in  alkalimetrical  exa- 
minations. 

/.  A  small  quantity  of  copper  and  arsenic  some- 
times contained  in  the  soil  may  be  determined  by  a 
special  experiment.  (See  No.  26.) 

VII.  Constituents  insoluble  in  dilute  hydrochloric  acid. 
— A  small  quantity  (about  5  or  10  grms.)  of  the 
residue  obtained  in  VI.,  is  heated  with  several  times  its 
weight  of  concentrated  sulphuric  acid,  until  the 
greater  part  of  the  acid  has  been  expelled.  By  this 


228  ASHES  OF  PLANTS. 

treatment  the  clay  is  decomposed.  The  nearly  dry 
residue  is  digested  with  dilute  hydrochloric  acid,  the 
solution  filtered  off,  and  analyzed  as  above,  omitting 
the  determination  of  silicic  acid. 

The  residue  left  by  hydrochloric  acid  is  boiled  for  a 
long  time  with  a  concentrated  solution  of  carbonate  of 
soda,  which  dissolves  the  silica  separated  by  the  sul- 
phuric acid.  The  filtered  solution  is  acidified  with 
hydrochloric  acid,  evaporated  to  dryness,  and  the 
silica  filtered  off. 

The  portion  insoluble  in  carbonate  of  soda  may  be 
a  mixture  of  sand,  feldspar,  and  other  minerals  not 
decomposed  by  sulphuric  acid,  which  maybe  separated 
to  some  extent  with  the  aid  of  a  magnifier.  In  order 
to  decompose  them  they  must  be  treated  as  in  the 
analysis  of  feldspar,  No.  80. 

The  greater  part  of  the  residue  obtained  in  VI.,  pre- 
viously to  treatment  with  sulphuric  acid,  may  be 
mechanically  separated,  with  tolerable  accuracy,  into 
its  constituents,  by  levigation.  The  residue  is  stirred 
up  with  much  water  by  means  of  a  feather,  and  the 
finer  suspended  portions,  consisting  chiefly  of  clay,N  are 
repeatedly  poured  off  until  only  the  grains  of  sand, 
feldspar,  &c.,  remain  behind.  - 


118.  ASHES  OF  PLANTS.* 

Salts  of  KO,  NaO,  CaO,  MgO,  A1203,  Fe2O3  and  MnO, 
with  01,  F,  SO3,  CO2,  and  SiO2. 

Manganese  does  not  occur  in  all  ashes,  and  is 
seldom  present  in  sufficient  quantity  to  determine. 
Fluorine  has  been  hitherto  found  only  in  the  stalks  of 
some  of  the  Oraminacese.  Alumina  is  an  essential  con- 
stituent of  the  ashes  of  the  Lycopodiacese,  but  is 

*  By  Professor  Stadeler. 


ASHES  OF  PLANTS.  229 

seldom  present  in  appreciable  quantity  in  other  ashes. 
Even  iodine,  bromine,  oxide  of  copper,  and  titanic 
acid  have  been  found,  though  generally  in  very  minute 
quantities,  in  some  ashes. 

The  process  of  analysis  differs  according  as  the 
ashes  do  or  do  not  contain  more  phosphoric  acid  than 
is  requisite  to  combine  with  the  sesquioxide  of  iron, 
protoxide  of  manganese,  lime,  magnesia,  and  alumina. 
To  the  former  (containing  more  phosphoric  acid)  belong 
those  of  seeds,  to  the  latter,  those  of  woods,  succulent 
plants,  &c. 

I.  Ashes  of  seeds. — About  50  grms.  of  the  seeds 
which  have  been  dried  in  the  air,  or  at  100°,  are 
thoroughly  carbonized  by  gentle  ignition  in  a  pla- 
tinum crucible;  the  carbonaceous  mass  is  powdered, 
moistened  with  water,  and  exposed  for  some  time  to 
the  air,  when  the  sulphides  are  converted  into 
sulphates ;  it  is  then  digested  with  concentrated  acetic 
acid,  water  added,  the  mixture  filtered,  and  the  residue 
washed  with  hot  water  till  the  washings  are  only 
slightly  acid  to  test  papers.  The  carbonized  mass  is 
thus  entirely,  or  almost  entirely,  freed  from  metallic 
chlorides;  it  is  introduced,  while  yet  moist,  into  a  pla- 
tinum crucible,  and  incinerated  as  far  as  possible  by  a 
protracted  gentle  ignition.  (At  a  bright  red  heat, 
phosphide  of  platinum  is  formed  and  the  crucible 
corroded.)  Finally,  a  few  drops  of  concentrated 
nitric  acid  are  added  to  the  ash,  which  is  then  ignited 
in  the  crucible,  the  cover  of  which  is  placed  against 
its  mouth,  until  the  last  traces  of  carbon  are  burnt  off, 
and  a  perfectly  white  ash  remains.  This  ash  is  added 
to  the  saline  mass  obtained  by  evaporating  the  acetic 
solution ;  the  mixture  is  gently  ignited  to  decompose 
the  acetates,  and  weighed. 

The  ash  is  dissolved  by  nitric  acid  in  a  carbonic 
acid  apparatus,  and  the  carbonic  acid  determined  from 
the  loss. 
20 


230  ASHES   OF  PLANTS. 

,The  solution  is  mixed  with  10  or  12  volumes  of 
water,  and  the  residue,  consisting  of  undissolved  silica 
(sometimes  also  of  sand)  and  charcoal,  is  collected  upon 
a  filter  (previously  dried  at  100°),  weighed,  carefully 
removed  from  the  filter,  and  digested  with  very  dilute 
solution  of  soda,  which  readily  dissolves  all  the  silica, 
except  that  present  in  the  form  of  sand  j  the  residue 
of  sand  and  charcoal  is  collected  upon  the  filter 
previously  employed;  its  weight,  after  being  dried  at 
100°,  is  deducted  from  the  total  weight  of  the  ash. 
The  weight  of  the  silicic  acid  is  determined  from  the 
loss. 

From  the  filtered  solution  containing  the  saline 
constituent,  the  chlorine  is  precipitated  by  nitrate  of 
silver,  an  excess  of  the  precipitate  removed  by  hydro- 
chloric acid,  the  sulphuric  acid  precipitated  by 
chloride  of  barium,  and  the  excess  of  baryta  separated 
by  careful  addition  of  sulphuric  acid. 

The  filtrate  is  evaporated  to  dryness,  the  residue 
treated  with  concentrated  hydrochloric  acid,  and  di- 
gested with  it  for  some  time,  in  order  completely  to 
expel  the  nitric  acid,  and  to  convert  any  pyrophos- 
phoric  acid  into  the  tribasic  form.  The  hydrochloric 
acid  is  expelled  as  far  as  possible,  a  sufficient  quantity 
of  water  afterwards  added,  and  the  solution  filtered 
from  the  undissolved  silica,  which  is  ignited,  weighed, 
and  calculated  together  with  that  previously  obtained. 

From  the  solution,  the  iron,  manganese,  alumina, 
lime,  and  magnesia,  are  precipitated  by  ammonia  as 
phosphates,  which  are  collected,  after  six  or  eight 
hours,  upon  a  filter,  ignited  and  weighed.  The  pre- 
cipitate is  dissolved  by  digestion  with  concentrated 
hydrochloric  acid,  the  free  acid  nearly  neutralized  with 
soda,  and  the  solution  mixed  with  acetate  of  soda,  when 
the  phosphates  of  sesquioxide  of  iron  and  alumina  are 
precipitated.  These  are  ignited  and  weighed,  and  if 
necessary  (unless  the  ignited  precipitate  has  a  pure 


ASHES   OF   PLANTS.  231 

brown  color),  separated  according  to  No.  19. — From 
the  filtrate,  the  lime  is  precipitated  by  oxalate  of  am- 
monia, and  the  magnesia  as  phosphate  of  magnesia- 
ammonia,  by  merely  adding  an  excess  of  ammonia ; 
the  phosphoric  acid  previously  in  combination  with 
the  lime  is  calculated  from  the  loss. — If  manganese  be 
present,  it  is  precipitated  together  with  the  phosphate 
of  magnesia-ammonia,  to  which  it  imparts  a  gray  or 
black  color  after  ignition.  The  separation  is  effected 
as  in  No.  26. 

The  solutions  from  which  the  phosphates  have  been 
precipitated  by  ammonia,  now  contain  only  the  alka- 
lies and  the  remainder  of  the  phosphoric  acid.  The 
latter  is  precipitated  (together  with  sulphuric  acid)  by 
chloride  of  barium,  and  the  excess  of  baryta  removed 
by  sulphuric  acid  or  by  neutral  carbonate  of  am- 
monia ;  the  filtrate  is  evaporated  to  dryness,  the  residue 
ignited,  and  the  alkalies  weighed  as  chlorides  or  sul- 
phates. For  their  separation,  see  No.  4. — The  preci- 
pitate produced  by  chloride  of  barium  is  exhausted 
with  nitric  acid,  sulphuric  acid  added  to  effect  the 
complete  separation  of  the  baryta,  and  the  phosphoric 
acid  precipitated  from  the  filtrate,  previously  mixed 
with  an  excess  of  ammonia,  as  phosphate  of  magnesia- 
ammonia. 

II.  Ashes  of  wood,  vegetables,  &c. — Of  those  vegetables 
which  yield  a  large  amount  of  ash,  50  grms.  may  be 
taken  for  examination ;  but  of  the  different  kinds  of 
wood,  which  are  usually  poorer  in  mineral  constituents, 
and  of  the  Graminacede,  the  ash  of  which  contains 
much  silica,  about  100  grms.  should  be  employed. 
The  substances  are  carbonized  in  a  platinum  crucible, 
and  the  mass  thrown  immediately  into  a  flat  porcelain 
dish,  where  it  generally  smoulders  for  a  long  time, 
and  is,  for  the  most  part,  converted  into  ash.  The 
incineration  is  completed  in  the  platinum  crucible. 

The  analysis  of  these  ashes  only  differs  from  that 


232  GUANO. 

of  the  preceding  in  that  these  contain  a  larger  quan- 
tity of  the  alkaline  earths  than  is  necessary  to  com- 
bine with  the  phosphoric  acid,  so  that  the  total 
amount  of  that  acid  is  separated  upon  adding  am- 
monia. The  precipitate  is  immediately  filtered  off,  and 
the  filtrate  mixed,  first  with  sulphide  of  ammonium, 
to  precipitate  the  manganese,  then  with  oxalic  acid  for 
the  lime,  and  lastly  with  phosphate  of  ammonia  to 
separate  the  magnesia.  Any  excess  of  phosphoric 
acid  may  be  separated,  as  directed  above,  from  the 
alkalies,  which  are  then  weighed  as  chlorides  or  sul- 
phates. 

The  stalks  of  the  Graminacese  usually  leave  an 
ash  which  cannot  be  completely  decomposed  by  nitric 
or  hydrochloric  acid.  The  weighed  silicate  remaining 
undissolved,  is  decomposed  most  conveniently  with 
hydrofluoric  acid,  and  the  bases,  previously  in  combi- 
nation with  silicic  acid,  may  then  be  estimated  in  the 
solution.  The  silicic  acid  is  determined  from  the 
loss.  In  this  case,  the  determination  of  the  charcoal 
and  sand  must,  of  course,  be  omitted. 

(See  also  for  other,  and,  in  part,  newer  and  better 
methods,  Liebig's  and  Kopp's  Jahresbericht;  1850,  p. 
603;  1857,  p.  582  and  584;  1859,  p.  693.) 


119.  GUANO. 

Guano  consists  of  the  partially  decomposed  excre- 
ment of  sea-birds.  It  contains  a  great  many  sub- 
stances, some  soluble,  others  insoluble  in  water.  The 
constituents  upon  which  depend  its  important  action 
and  application  as  a  manure  are:  organic,  chiefly 
nitrogenized  matters ;  salts  of  ammonia ;  phosphates, 
especially  phosphate  of  lime ;  and  salts  of  the  alka- 
lies. The  amount  of  these  constituents  indicates  the 


GUANO.  283 

value  of  the  guano.  It  is  important  to  test  this 
manure,  since  different  specimens  consist  not  only  of 
various  kinds  of  genuine  guano  of  different  degrees 
of  richness,  but  samples  also  come  into  the  market 
which  are  adulterated  with  common  earth,  loam, 
lime,  sand,  pebbles,  and  crude  common  salt  or  Glau- 
ber's salt. 

Genuine  guano  presents  the  appearance  of  a  moist 
yellowish-brown  earth,  mixed  here  and  there  with 
white  fragments  or  lumps.  Very  few  and  rare  speci- 
mens are  white.  It  has  a  peculiar  excrementitious  or 
urinous  odor,  and  a  feeble  penetrating  saline  taste. 

It  is  chemically  tested  in  the  following  manner : — 

I.  The  guano  is  mixed,  in  a  dish,  with  hydrate  of 
lime  (slaked  lime  stirred  with  water  to  a  thin  cream), 
when  it  should  emit,  especially  when  heated,  a  power- 
ful odor  of  ammonia.     In  order  to  compare  different 
specimens,  the  same  quantity,  say  J  oz.  of  each,  is  taken. 
Since  the  value  depends  partly  upon  the  amount  of 
ammonia  present,  the  better  sorts  of  guano  will  evolve 
the  stronger  odor  of  that  gas. 

II.  Two  ounces  (or  from  50  to  60  grins.)  of  guano, 
finely  powdered  and  uniformly  mixed,  are  weighed  in 
a  counterpoised  porcelain  capsule,  and  heated  on  a 
water-bath  until  it  is  perfectly  dry  and  suffers  no  far- 
ther diminution  of  weight.    The  loss  of  weight  expresses 
the  amount  of  moisture  contained  in  the  guano.     Good 
guano  loses  only  between  8  and  15  per  cent,  of  water, 
but  if  fraudulently  moistened,  it  may  lose  20  per  cent., 
or  even  more. 

III.  Half  an  ounce  (or  from  15  to  20  grms.)  of  guano 
is  weighed,  and  heated  over  a  large  spirit-lamp,  or 
gas-burner,  in  a  porcelain  or  platinum  crucible,  with 
free  access  of  air,  until  all  organic  matter  has  burnt 
off',  and  the  guano  is  converted  into  a  white  or  grayish 
ash.     Good  guano,  when  treated  in  this  way,  leaves 
from  30  to  35  per  cent,  of  ash,  while  bad  guano  leaves 

20* 


234:  GUANO. 

from  60  to  80  per  cent.,  and  that  which  has  been  fraud- 
ulently adulterated  leaves  still  more.  The  ash  of  gen- 
uine guano,  whether  of  good  or  bad  quality,  is  always 
white  or  grayish  ;  a  yellow  or  reddish  color  bespeaks 
an  admixture  of  clay  or  earth.  Good  guano,  when 
first  heated,  evolves  white  vapors,  with  a  powerful 
odor  of  ammonia. 

IV.  A  similar  quantity  of  guano  is  mixed,  in  a  dish, 
with  several  times  its  volume  of  water ;  heat  is  then 
applied,  and  the  mass  thrown  upon  a  small  filter  (pre- 
viously dried  in  the  water- bath  and  weighed) ;   the 
residue  on  the  filter  is  washed  with  hot  water  till  a 
small  portion  of  the  washing- water  is  not  rendered  tur- 
bid by  adding  chloride  of  calcium  and  ammonia.    The 
filter,  with  the  washed  guano,  is  then  thoroughly  dried 
in  a  water-bath  and  weighed.     The  better  the  quality 
of  the  specimen,  the  less   insoluble  residue  will  be 
obtained.    Gfood  samples  of  guano  leave  from  40  to  45 
per  cent.,  those  of  bad  quality  as  much  as  70  or  80. 
If  the  guano  be  adulterated  with  common  salt  or  with 
Glauber's  salt,  it  will  behave  to  this  test  like  a  genuine 
specimen,  but  furnish  a  greater  quantity  of  ash  in  Ex- 
periment III. 

V.  The  guano  under  examination,  may  be  treated 
with  moderately  strong  hydrochloric  acid.    Good  guano 
effervesces  but  slightly ;  a  specimen  of  guano  adulte- 
rated with  chalk,  would  effervesce  strongly,  and  would 
leave  a  proportionally  larger  quantity  of  ash  in  Ex- 
periment III. 

VI.  The  ash  obtained  in  III.  is  dissolved  in  dilute 
hydrochloric  acid,  which  should  give  rise  only  to  slight 
effervescence,  if  the  guano  be  unadulterated.     The  so- 
lution is  filtered  from  the  residue,  the  latter  washed, 
dried,  thoroughly  burnt,  together  with  the  filter  in  a 
weighed  crucible,  over  the  spirit-lamp,  and  weighed. 
This    insoluble    residue,   consisting   partly   of    sand, 


GUANO.  235 

amounts,  in  good  (undried)  guano;  to  only  1  or  2  per 
cent. 

VII.  The  filtered  hydrochloric  solution  is  mixed 
with  a  slight  excess  of  ammonia.     The  precipitate  thus 
produced  consists  almost  entirely  of  phosphate  of  lime. 
It  is  filtered  off,  washed,  dried,  and  ignited ;  its  quan- 
tity in  good  guano  amounts  to  20  or  25  per  cent. 

VIII.  The  filtrate  from  this  precipitate  should  fur- 
nish only  slight  indications  of  lime  on  addition  of 
oxalic  acid ;  but  if  the  guano  be  adulterated  with  chalk, 
this  reagent  will  produce  a  very  considerable  precipi- 
tate.    This  solution  ought  therefore  to  contain  only  the 
alkaline  salts,  amounting  to  5  or  10  per  cent,  of  the 
original  undried  guano.     In  order  to  determine  them 
directly,  which  is  generally  unnecessary  for  practical 
purposes,  the  solution  must  be  mixed  with  some  more 
chloride  of  ammonium,  and  evaporated  to  dryness; 
the  residue  is  heated  to  volatilize  the  excess  of  chloride 
of  ammonium,  and  to  convert  the  sulphates  into  chlo- 
rides, weighed,  and  farther  treated  as  in  No.  4. 

IX.  The  aqueous  solution,  which  was  obtained  in 
the  lixiviation-test  (IV.),  and  of  which  a  fresh  quantity 
may  be  prepared  so  as  to  be  saturated,  has  a  brown 
color  and  a  saline  taste.     When  evaporated  it  evolves 
ammonia,  emits  a  urinous  odor,  and  leaves  a  brown 
crystalline   mass,  consisting   chiefly   of  sulphates  of 
potassa  and  soda,  chloride  of  ammonium,  oxalate  and 
phosphate   of  ammonia.     This  solution  exhibits  the 
following  reactions : — 

When  mixed  with  hydrate  of  potassa,  it  smells 
strongly  of  ammonia. 

With  chloride  of  ammonium,  ammonia,  and  sulphate 
9f  magnesia,  it  gives  an  abundant  pulverulent  precipi- 
tate or  phosphate  of  magnesia-ammonia. 

When  acidified  with  acetic  acid  and  tested  with 
chloride  of  calcium,  it  gives  a  copious  precipitate  of 
oxalate  of  lime. 


236  GUANO. 

After  addition  of  excess  of  hydrochloric  acid,  it 
gives,  with  chloride  of  barium,  a  considerable  precipi- 
tate of  sulphate  of  baryta. 

X.  When  guano  is  exahusted  with  cold  water,  and 
the  residue  digested  with  a  weak  solution  of  caustic 
soda,  uric  acid  is  extracted.     The  solution  is  filtered, 
and  feebly  acidulated  with  hydrochloric  acid,  when 
the  uric  acid  is  precipitated.     After  being  filtered  off 
and  washed,  it  is  easily  soluble  in  caustic  potassa,  and 
may  be  reprecipitated  by  hydrochloric  acid.     If  it  be 
dissolved  in  warm  dilute  nitric  acid,  the  solution  evapo- 
rated  to   dryness,   and   the    residue   moistened   with 
carbonate  of  ammonia,  a  fine  purple-red  color  is  pro- 
duced. 

XI.  The  quantity  of  organic  matter  can  be  estimated 
directly  only  by  an  ultimate  organic  analysis.      In 
good  undried  guano  it  amounts,  taking  the  ammonia 
into  account,  to  about  50  per  cent. 

XII.  The  exact  determination  of  the  nitrogen  re- 
quires also  an  ultimate  analysis.     This  element  should 
amount  to  12  or  14  per  cent.;  bad  samples  contain 
only  from  1  to  6  per  cent.     The  quantity  of  nitrogen, 
may,  however,  be  approximately  determined  by  the 
following  method,  which  therefore  allows  us  to  ascer- 
tain rapidly  the  value  of  different  specimens  of  guano. 
It  depends  upon  the  circumstance  that  when  guano  is 
treated  with  a  solution  of  chloride  of  lime(hypochlorite 
of  lime),  the  nitrogen  of  the  organic  matter  and  of  the 
ammoniacal  salts  is  evolved  as  gas.*     Instead  of  col- 
lecting and  measuring  the  gas  evolved,  which  would 
be  scarcely  practicable,  on  account  of  the  violent  effer- 
vescence, the  volume  of  water  which  is  expelled  by 
the  gas  is  ascertained  by  means  of  the  simple  apparatus 

*  Farther  experiments  are  required  to  show  that  all  the  nitrogen 
is  here  evolved  in  the  gaseous  state,  and  to  ascertain  how  the 
various  nitrogen-compounds  behave  with  chloride  of  lime. 


GUANO. 


237 


represented  in  the  figure ;  it  consists  of  a  flask  capable 
of  containing  about  J  pint,  provided  with  a  narrow 

Fig.  28. 


gas-delivery-tube  bent  twice  at  right  angles.  One 
limb,  rather  the  shorter  of  the  two,  is  passed,  air-tight, 
through  the  cork  of  the  flask,  and  bent  upwards  to 
prevent,  as  far  as  possible,  the  escape  of  bubbles  of  gas. 
This  tube  descends  nearly  to  the  bottom  of  the  flask. 
A  second  very  narrow  short  tube  is  also  passed  through 
the  cork,  and  serves  for  the  escape  of  air  when  the  cork 
is  introduced.  The  longer  limb  of  the  delivery-tube 
dips  into  a  tall  cylinder  or  tube,  which  is  graduated 
to  cubic  centimeters,  or  cubic  inches.  The  flask  is 
half-filled  with  solution  of  chloride  of  lime  ;*  1  grm. 
of  guano  is  then  weighed  in  the  small  glass  vessel  (the 
end  of  a  test-tube)  in  which  a  few  small  shot  have  been 
placed,  in  order  that  it  may  float  upright.  With  the 
aid  of  the  handle  of  iron-wire  shown  in  the  figure,  the 
tube  is  let  down  so  as  to  float  upon  the  surface  of  the 
solution  of  chloride  of  lime;  the  cork  with  the  tube  is 

*  This  solution  must  be  carefully  prepared  and  kept  in  a  dark 
place,  in  a  closed  vessel.  It  must  contain  an  excess  of  hydrate  of 
lime,  and  therefore  need  not  be  perfectly  clear. 


238  OXALATE   AND  PHOSPHATE   OF   LIME. 

then  tightly  adjusted,  the  orifice  of  the  smaller  tube 
closed  with  wax,  and  the  flask  shaken  so  that  the  little 
vessel  may  fill  and  sink.  A  volume  of  liquid  equal 
to  that  of  the  nitrogen  evolved  from  the  guano  then 
flows  into  the  graduated  cylinder ;  when  no  more  liquid 
passes  over,  the  cylinder  is  depressed  so  as  to  bring 
the  liquid  to  the  same  level  as  that  in  the  generating- 
flask ;  the  wax  plug  is  then  removed,  the  cork  with- 
drawn, and  the  liquid  still  contained  in  the  delivery- 
tube  is  allowed  to  run  into  the  cylinder,  where  the 
whole  is  carefully  measured.  1  grm.  of  good  guano 
evolves  between  70  and  80  cub.  cents,  of  gas. 


120.  OXALATE  AND  PHOSPHATE  OF  LIME. 

A  mixture  of  these  two  salts  dissolves  in^nitric  acid 
without  effervescence,  and  is  precipitated  from  the 
solution  by  ammonia.  If  it  be  digested,  when  freshly 
precipitated,  with  acetic  acid,  the  phosphate  of  lime 
may  be  dissolved,  while  the  oxalate  is  left. 

If  the  mixture  be  previouly  ignited,  it  dissolves  in 
nitric  acid  with  effervescence,  and  ammonia  then  pre- 
cipitates from  the  solution  only  the  phosphate  of  lime, 
while  the  lime  which  had  been  in  combination  with 
oxalic  acid  remains  in  solution,  and  may  be  precipitated 
by  oxalate  of  ammonia,  and  quantitatively  determined. 
Phosphate  of  lime,  when  freshly  precipitated,  may  be 
recognized  by  the  yellow  color  which  it  assumes  when 
moistened  on  the  filter,  with  nitrate  of  silver.  It  is 
analyzed  as  in  No.  13. 

If  the  two  salts  be  dissolved  in  the  smallest  possible 
quantity  of  hydrochloric  acid,  and  the  solution  mixed 
with  an  excess  of  acetate  of  soda,  the  oxalate  of  lime 
is  precipitated,  while  the  phosphate  remains  in  solu- 
tion ;  from  the  latter,  the  lime  may  be  precipitated  -by 


OXALATE  AND  PHOSPHATE  OF  LIME.  239 

oxalate  of  ammonia,  and  afterwards  the  phosphoric 
acid  by  sulphate  of  magnesia  and  ammonia,  as  in  No.  9. 

When  the  mixture  of  the  two  salts  is  treated  with 
concentrated  sulphuric  acid,  oxalic  acid  is  converted 
into  carbonic  acid  and  carbonic  oxide,  so  that  by 
employing  the  apparatus  described  in  the  article  upon 
alkalimetry,  its  amount  may  be  inferred  from  the  loss 
of  weight. 

By  gently  heating  the  mixture  with  an  excess  of 
finely-powdered  binoxide  of  manganese  or  neutral 
chromate  of  potassa,  or  with  binoxide  of  lead  and  di- 
lute sulphuric  acid,  all  the  oxalic  acid  is  converted  into 
carbonic  acid,  the  quantity  of  which  may  be  determined 
by  the  use  of  the  apparatus  above  alluded  to.  2  equivs. 
of  carbonic  acid  correspond  to  1  equiv.  of  oxalic  acid. 

If  binoxide  of  lead  be  employed  in  this  operation, 
the  quantitative  determination  of  the  phosphoric  acid 
may  be  effected  at  the  same  time;  for  this  purpose, 
the  mixture  is  digested  for  some  time,  to  liberate  the 
whole  of  the  phosphoric  acid;  several  volumes  of 
alcohol  are  then  added,  in  order  to  separate  the  sul- 
phate, of  lime,  the  solution  filtered,  and  the  residue 
washed  with  alcohol.  From  the  filtrate,  after  the 
evaporation  of  the  alcohol,  the  phosphoric  acid  may 
be  precipitated  by  sulphate  of  magnesia  and  ammonia. 

A  very  accurate  method  of  estimating  oxalic  acid 
consists  in  converting  it  into  carbonic  acid  by  means 
of  a  solution  of  terchloride  of  gold,  weighing  the 
reduced  gold,  and  calculating  thence  the  amount  of 
oxalic  acid  ;  3  equivs.  of  the  latter  reduce  1  equiv.  of 
gold  =  197. 

For  this  purpose  the  mixture  of  the  two  salts  is 
dissolved  in  the  smallest  possible  quantity  of  hydro- 
chloric acid  (a  large  excess  impedes  the  reduction  in 
gold),  mixed  with  an  excess  of  a  solution  of  terchloride 
of  gold,  or  better,  of  sodio-chloride  of  gold,  diluted 
with  much  water,  and  heated  to  ebullition.  The  re- 


240  ALKALIMETRY. 

duced  coherent  gold  is  easily  washed ;  it  is  to  be  dried, 
ignited,  and  weighed. 

The  excess  of  gold  is  removed  from  the  solution  by 
sulphuretted  hydrogen,  or  by  boiling  with  oxalic  acid, 
and  the  phosphoric  acid  and  lime  are  then  separated 
and  estimated  as  in  No.  13. 


121.  ALKALIMETRY. 

The  specimens  of  potashes  and  soda-ashes  met  with 
in  commerce  contain  very  variable  quantities  of  foreign 
substances.  The  amount  of  carbonated  alkali,  upon 
which  their  value  alone  depends,  varies  between  40 
and  95  per  cent. 

The  potashes  contain  chiefly  chloride  of  potassium, 
sulphate,  silicate,  and  phosphate  of  potassa,  and  carbo- 
nate, phosphate,  ajid  silicate  of  lime. 

The  soda  generally  contains  chloride  and  sulphide 
of  sodium,  sulphate,  silicate  and  hyposulphite  of  soda, 
and  often  also  hydrate  of  soda. 

The  amount  of  alkaline  carbonate  present  in  the 
sample,  may  be  determined  by  several  methods. 

I.  By  the  standard  solution  test,  i.  e.,  by  exactly  neu- 
tralizing a  weighed  portion  with  dilute  sulphuric  acid  of 
known  strength. 

In  order  to  prepare  the  test-acid,  a  known  quantity, 
say  70  grms.  of  concentrated  sulphuric  acid,  are  diluted 
with  600  grms  of  water. 

5  grms.  of  pure  anhydrous  carbonate  of  soda  are 
weighed,  dissolved  in  hot  water,  and  the  solution 
colored  blue  with  a  little  tincture  of  litmus. 

The  test-acid  is  then  added  to  the  solution,  from  a 
burette,  very  carefully  as  the  point  of  neutralization  is 
approached,  until  the  color  is  just  changed  to  red,  and 


ALKALIMETRY.  241 

streaks  which  are  made  with  the  liquid  upon  litmus- 
paper,  remain  red  after  drying. 

The  number  of  measures  of  acid  employed  is  then 
observed,  and  the  whole  of  the  test-acid  is  diluted  with 
so  much  water,  that  exactly  100  measures  are  required 
to  neutralize  5  grms.  of  pure  carbonate  of  soda.  This 
stock  of  test-acid  is  preserved  in  a  well-stopped  bottle. 
It  indicates  immediately  the  percentage  of  caustic  or 
carbonated  alkali  in  a  specimen  of  potashes  or  soda, 
provided  that  a  quantity  of  the  sample  be  employed, 
which  is  equivalent  to  5  grms.  of  carbonate  of  soda. 

100  measures  of  test  acid  saturate  5.000  grms.  of  oarb.  of  soda. 
100        "  "  "         2  935      "      of  soda. 

100        "  "  "         6.487      "      of  carb.  of  potassa. 

100        "  "  «         4.421      "      of  potassa. 

So  that  if  6'487  grms.  of  a  sample  of  potashes  be 
taken,  the  number  of  measures  of  acid  employed  will 
express,  directly,  the  percentage  of  carbonate  of  potassa, 
or  if  4.421  grms.  be  used,  of  anhydrous  potassa,  con- 
tained in  the  specimen. 

Instead  of  sulphuric  acid,  pure  crystallized  oxalic 
acid  may  be  very  conveniently  employed  for  preparing 
the  test-solution.  An  equivalent  of  the  acid  (63  grms.) 

Fig.  29. 


is  introduced  into  a  flask  of  1  litre  capacity,  which  is 
then  two-thirds  filled  with  water ;  the  acid  is  allowed 
21 


242  ALKALIMETRY. 

to  dissolve,  and  so  much  water  added  that  the  whole 
solution  may  measure  1  litre  or  1000  cubic  centime- 
tres, at  17.5°  C. 

One  hundred  cub.  cents,  of  this  test-acid  will  then 
exactly  neutralize  TV  of  an  equivalent  proportion  of 
either  alkali.  It  is  therefore  necessary  to  weigh  out 
y'g  of  an  equivalent  proportion  (in  grammes)  of  the 
anhydrous  alkali  to  be  tested,  that  is,  6*92  grms.  of 
potashes,  or  5'32  grms.  of  soda-ash.  In  order  to  obtain 
perfectly  accurate  results,  the  process  is  conducted  as 
follows :  The  solution  of  alkali  to  be  tested,  is  intro- 
duced into  a  flask  colored,  with  tincture  of  litmus, 
and  the  test-acid  poured  into  it  from  a  burette,  until 
the  color  changes  from  blue  to  violet,  and  the  effer- 
vescence is  very  feeble.  The  solution  is  now  heated  to 
ebullition,  and  more  acid  added  until  the  color  has 
become  decidedly  red.  5  or  10  cub.  cents,  of  the  test- 
acid  are  then  added  in  excess ;  the  alkali  will  be  now 
supersaturated.  By  boiling,  agitating,  and  finally  suck- 
ing out  with  a  glass  tube,  the  last  traces  of  carbonic 
acid  are  removed  r  -now  required  to  determine 
exactly  how  far  tne  neutralization  of  the  alkali  has 
been  exceeded ;  for  this  purpose  a  standard  solution 
of  caustic  soda  is  employed,  of  such  strength  that  it 
is  exactly  neutralized  by  an  equal  volume  of  the  test- 
acid  ;*  this  solution  is  added  from  a  burette  graduated 
to  T*$  cub.  cent.,  when  the  red  color  rapidly  changes 
to  violet,  and  then  suddenly  to  pure  blue.  The  num- 
ber of  cubic  centimetres  of  soda-solution  employed,  is 
then  deducted  from  the  volume  of  test-acid  previously 
added ;  the  remainder  gives  the  percentage  of  pure 
alkaline  carbonate. 

*  This  solution  of  soda  must  be  perfectly  free  from  carbonic 
acid.  In  order  to  preserve  it  in  that  state,  the  bottle  is  closed 
with  a  cork,  through  which  passes  an  ordinary  chloride-of-calcium- 
tube,  open  at  both  ends,  and  filled  with  a  mixture  of  Glauber's 
salt  and  quicklime  in  powder. 


ALKALIMETRY. 


243 


The  dropping-tubes  or  burettes  employed  for  these 
analyses  with  standard  solutions,  are  made  of  different 
forms.  The  commonest  is  that  represented  in  Fig.  30  «, 

Fig.  30. 


and  consists  of  a  glass  tube,  closed  at  one  end,  about 
0.25  metre  (or  12  inches)  long,  and  0.01  metre  (or  f 
inch)  in  diameter  ;  into  the  lower  part  of  this  tube  is 
cemented  another,  very  much  narrower,  which  is  fixed 
parallel  with  the  larger  tube ;  the  extremity  of  the 
small  tube  is  bent  outwards  and  sharply  cut  off,  so 
that  the  liquid  may  be  conveniently  poured  from  it. 
The  whole  of  the  vessel  is  divided  into  known  volumes, 
and  it  is  preferable  to  take  from  25  to  50  cub.  cents., 
and  to  divide  these  into  fractional  parts.  The  zero 
should  be  placed  at  the  top  of  the  scale,  below  the 
level  of  the  orifice  of  the  spout. 

Another  form  is  that  shown  in  Fig.  30  b,  which 
consists  of  a  single  divided  tube  furnished  at  the  top 
with  a  spout,  and  with  an  orifice  for  pouring  in  the 
liquid. 

A  third  form  of  burette,  which  is  the  most  suitable 


244 


ALKALIMETRY. 


and  convenient,  and  can  be  very  easily  made  by  the 
analyst  himself,  is  that  represented  by  the  adjoining 
figure.  It  consists  of  a  glass  tube,  about  0.01  metre 

Fig.  31. 


in  diameter,  which  is  divided  into  25  or  50  cubic  cen- 
timetres, and  drawn  out  to  a  point  at  the  lower  ex- 
tremity. To  this  open  point  is  attached  a  narrow  tube 
of  vulcanized  caoutchouc,  about  an  inch  long,  and  in 
the  lower  end  of  this  tube  is  inserted  a  short  glass  tube 
drawn  out  to  a  narrow  point  and  cut  smoothly  off; 
this  tube  serves  for  dropping  the  liquid  out,  and  is 


ALKALIMETRY.  245 

tightly  connected  with  the  graduated  tube  in  such  a 
manner  that  a  considerable  interval  may  be  left 
between  the  ends  of  the  two  tubes.  Upon  this  part 
of  the  caoutchouc  tube  is  fixed  a  clamp  made  of  thick 
brass  wire,  shown  with  its  actual  dimensions,  in  the 
accompanying  figure,  so  constructed  that  the  caout- 

Fig.  32. 


chouc  tube  may  be  opened  by  pressing  upon  the  two 
ends  of  the  clamp,  and  closed  when  the  pressure  is 
removed.  In  order  to  use  this  tube,  it  is  fixed  in  a 
stand,  in  a  vertical  position,  above  the  vessel  contain- 
ing the  liquid  to  be  tested.  By  pressing  upon  the  ends 
of  the  little  clamp,  the  caoutchouc  tube  is  opened,  and 
the  liquid  allowed  to  flow  out,  even  in  single  drops,  if 
required.  At  the  commencement  of  the  operation,  the 
tube  is  filled  with  the  test-liquid,  a  portion  of  which 
is  then  made  to  flow  out,  by  pressing  upon  the  clamp 
until  it  stands  exactly  at  the  zero  of  the  scale. 

II.  By  determining  the  carbonic  acid  evolved. 

The  carbonic  acid  is  liberated  from  a  weighed  por- 
.tion  of  the  alkali,  in  an  apparatus  which  is  previously 
weighed  (together  with  the  acid  used  to  effect  the 
decomposition),  and  the  carbonic  acid  determined  from 
the  loss  of  weight. 

The  apparatus  employed  for  this  purpose  may  be 
21* 


246  ALKALIMETRY. 

arranged  in  different  ways.  That  represented  in  the 
adjoining  figure,  of  about  J  its  real  dimensions,  will 
render  apparent  the  general  principle,  upon  which  they 
are  constructed,  and  will  itself  fully  answer  the  pur- 
pose. It  consists  of  a  small  light  flask,  closed  by  a 
cork  perforated  with  two  holes,  in  one  of  which  is 
inserted  a  tube  filled  with  fragments  of  chloride  of 
calcium,  and  in  the  other,  a  narrow  glass  tube,  running 

Fig.  33. 


nearly  parallel  with  the  inner  wall  of  the  flask,  and 
reaching  almost  to  the  surface  of  the  liquid ;  above  the 
cork,  this  tube  is  bent  at  right  angles. 

The  specimen  to  be  examined  is  weighed  in  the 
flask,  the  latter  about  one-third  filled  with  water,  and 
the  small  tube  full  of  acid  introduced  with  a  pair  of 
pincers ;  this  tube  must  be  of  such  a  length  that  it 
cannot  fall  down  in  the  flask,  but  may  assume  the 
position  indicated  in  the  figure.  Sulphuric  acid  is  to 
be  preferred  for  effecting  the  decomposition  of  the 
carbonate,  and  should  be  employed  in  quantity  more 
than  sufficient  to  expel  the  whole  of  the  carbonic  acid. 
(B'or  the  carbonates  of  lime,  baryta,  and  lead,  nitric 


ALKALIMETRY.  247 

acid  must  be  employed). — The  cork,  with  the  chloride- 
of-calcium-tube,  and  the  bent  tube  is  then  introduced, 
air-tight,  into  the  neck  of  the  flask,  the  whole  appara- 
tus accurately  weighed,  and  the  orifice  of  the  bent  tube 
perfectly  closed  with  a  small  cork  or  with  wax. 

The  flask  is  then  carefully  inclined  so  that  a  small 
quantity  of  the  acid  may  run  out  of  the  tube  and  de- 
compose the  carbonate.  The  carbonic  acid  which  is 
evolved  escapes  through  the  chloride-of-calcium-tube, 
in  which  any  water  which  may  have  been  carried  off 
with  it  is  retained.  No  fresh  acid  is  allowed  to  flow 
out  of  the  tube  until  the  effervescence  caused  by  the 
first  portion  has  ceased,  and  does  not  recommence  upon 
gentle  agitation.  When,  at  length,  the  effervescence 
has  entirely  ceased,  so  that  the  salt  is  completely  de- 
composed, the  plug  is  removed  from  the  small  tube 
and  suction  applied,  by  the  mouth,  to  the  tube  contain- 
ing chloride  of  calcium,  until  the  air  passing  through 
the  flask  no  longer  tastes  of  carbonic  acid.  In  very 
exact  experiments,  a  second  chloride-of-calcium4ube 
must  be  attached  to  the  small  bent  tube,  to  retain  the 
moisture  of  the  air. 

1.  Potashes. — The  amount  of  water  is  ascertained 
by  heating  the  specimen,  for  some  time,  to  about  200°. 
For  this  purpose  from  2  to  5  grms.  of  potashes  may 
be  taken. 

In  order  to  determine  immediately,  without  calcula- 
tion, the  percentage  of  potassa  in  carbonate  of  potassa, 
by  means  of  the  above  apparatus,  3.14  grms.  of  the 
specimen  must  be  taken.  Since  3.14  grms.  of  pure 
carbonate  of  potassa  evolve  1.00  grm.  of  carbonic  acid, 
the  number  of  centigrammes  of  carbonic  acid  evolved 
will  represent  the  percentage  of  carbonate  of  potassa. 

2.  Soda. — 2.41  grms.  of  soda  are  employed.    This  is 
the  quantity  of  pure  carbonate  of  soda  which  evolves 
1.00  grm.  of  carbonic  acid. 

Should  caustic  soda  be  contained  in  the  specimen, 


248  VALUATION  OF   MANGANESE  ORES. 

which  may  be  known  by  the  alkaline  reaction  of  the 
solution  after  adding  an  excess  of  chloride  of  barium, 
the  following  modification  of  the  process  is  necessary  : 

2.41  grms.  of  the  anhydrous  sample  are  mixed  with 
about  8  parts  of  pure  quartz-sand,  and  about  J  part  of 
powdered  carbonate  of  ammonia;  the  mixture  is  moist- 
ened with  water,  and,  after  some  time,  gently  heated 
till  all  water  and  ammonia  are  expelled.  The  dry 
residue  is  then  treated,  as  usual,  in  the  above  appa- 
ratus. 

In  order  to  prevent  any  inaccuracy  arising  from  the 
presence  of  sulphide  of  sodium  or  hyposulphite  of  soda 
in  the  specimen,  a  solution  of  chromate  of  potassa  is 
added  previously  to  the  evolution  of  carbonic  acid,  in 
order  to  oxidize  these  impurities. 


122.  VALUATION  OF  MANGANESE  ORES. 

Good  manganese  ore,  which  consists  almost  entirely 
of  binoxide  of  manganese,  is  crystalline,  yields  a  black 
powder,  and,  after  being  dried  at  a  gentle  heat,  gives 
no  water,  or  only  traces,  when  heated  to  redness.  Man- 
ganese ore,  however,  generally  contains  foreign  mine- 
rals, especially  the  hydratedsesquioxide  of  manganese. 
In  order  to  determine  the  amount  of  binoxide,  or,  in 
other  words,  of  available  oxygen,  several  methods  may 
be  employed. 

I.  A  weighed  quantity  of  the  manganese  ore,  pow- 
dered as  finely  as  possible,  is  introduced  into  the  appa- 
ratus employed  for  the  quantitative  estimation  of  car- 
bonic acid  (Fig.  34),  where  it  is  brought  in  contact  with 
sulphuric  acid  and  a  solution  of  oxalic  acid,  when  sul- 
phate of  protoxide  of  manganese  is  produced,  since  all 
the  available  oxygen,  which  may  be  regarded  as  in 


VALUATION   OF   MANGANESE   ORES.  249 

combination   with    the   protoxide   of    manganese,    is 
evolved  in  the  form  of  carbonic  acid. 

Fig.  34. 


One  equiv.  of  pure  binoxide  of  manganese  =  43.6, 
yields  2  equivs.  =  44  of  carbonic  acid.  So  that  0.99 
grm.  of  binoxide  of  manganese  evolves  1.00  grm.  of 
carbonic  acid.  It  is  best  to  employ  three  times,  that 
quantity  of  the  manganese  ore,  viz :  2.97  grms.,  which 
are  mixed  with  a  solution  of  2.5  grms.  of  neutral 
oxalate  of  potassa ;  the  sulphuric  acid  is  allowed  to 
flow  into  this  mixture,  and  the  amount  of  carbonic 
acid  evolved  is  divided  by  3.  The  quotient  expresses 
the  percentage  of  binoxide  of  manganese  contained  in 
the  ore. 

II.  The  finely-divided  manganese  ore  is  weighed, 
and  mixed  with  water,  in  a  flask  capable  of  being 
tightly  closed ;  several  bright  strips  of  copper,  previ- 
ously weighed,  are  then  introduced,  and  a  quantity  of 
hydrochloric  acid  added.  The  flask  is  then  closed 
with  a  cork  and  narrow  tube,  and  the  contents  digested 
until  all  the  manganese  has  dissolved,  care  being  taken 
that  no  chlorine  is  evolved.  The  liquid  is  then  heated 


250  CHLORIMETRY. 

to  ebullition  for  a  quarter  of  an  hour,  the  flask  closed 
air-tight,  and  allowed  to  cool;  the  solution  is  poured 
off,  the  residual  copper  washed,  first  with  very  dilute 
hydrochloric  acid,  then  with  pure  water,  dried,  and 
weighed.  2  equivs.  of  copper  =  63.4  parts,  require  for 
their  conversion  into  subchloride,  1  equiv.  =  71  parts 
of  chlorine. 

Then  63.4  :  71  as  the  amount  of  copper  dissolved  is 
to  x  (the  amount  of  chlorine  sought). 

1.22  grms.  of  pure  binoxide  of  manganese  evolve 
1.00  grm.  of  chlorine,  and  therefore  are  capable  of 
effecting  the  solution  of  1.78  grms.  of  copper. 


123.  CHLORIMETRY. 

The  "bleaching  powder''1  of  commerce  is  a  variable 
mixture  of  bypochlorite  of  lime  and  chloride  of  cal- 
cium, with  hydrate  of  lime.  When  treated  with  an 
acid,  it  evolves  the  whole  of  the  chlorine  in  a  free 
state.  In  order  to  determine  its  value,  i.  e.,  the  amount 
of  available  chlorine  which  it  contains,  different 
methods  are  employed. 

I.  Fourteen  grms.  of  pure  arsenious  acid  are  dis- 
solved in  solution  of  potassa,  and  so  much  water  added 

Fig.  35. 


CHLORIMETRY. 


251 


that  the  liquid  may  occupy  2000  divisions  of  the 
graduated  burette.  100  measures,  therefore,  of  this 
solution  contain  0.7  grm.  of  arsenious  acid,  and  the 
solution  of  chlorine  which  is  required  to  convert  this 
into  arsenic  acid,  contains  0.5  grm.  of  chlorine,  since  1 
equiv.=  99  of  arsenious  acid,  requires,  for  its  conver- 
sion into  arsenic  acid,  2  equivs.=  71  of  chlorine. 

Five  grras.  of  chloride  of  lime  are  weighed  off,  inti- 
mately mixed  with  water,  by  trituration,  rinsed  into  a 
cylindrical  (Fig.  36)  glass,  and  so  much  water  added 
that  the  whole  may  occupy  200  measures  of  the 
burette. 


Figs.  36. 


37. 


39. 


One  hundred  measures  of  the  arsenic-solution  are 
then,  by  aid  of  the  pipette  (Fig.  37),  introduced  into  a 
beaker,  diluted  with  water,  an  excess  of  hydrochloric 
acid  added,  and  the  liquid  coloured  with  one  or  two 
drops  of  sulph-indigotic  acid. 

The  solution  of  chloride  of  lime  is  well  mixed  by 
agitation,  introduced  into  the  burette  (Fig.  39),  and 
added  to  the  colored  arsenic-solution  until  the  color 
just  disappears.  The  solution  of  chloride  of  lime 
required  to  produce  this  effect  contains  0.5  grm.  of 
chlorine. 

For  example,  if  90  measures  of  the  solution  of  chlo- 
ride of  lime  had  been  employed,  the  5  grms.  of  chloride 


252  ANALYSIS  OF  NITRE. 

of  lime  would  have  contained  1.111  grms.  of  chlorine, 
or  22.22  per  cent. 

Perfectly  pure  chloride  of  lime  (Ca  C1  +  CaO,  CIO), 
which  is  never  met  with  in  commerce,  contains  48.9 
per  cent,  of  available  chlorine. 

II.  A  weighed  quantity  of  chloride  of  lime  is  mixed 
with  water,  in  a  flask,  an  excess  of  protochloride  of 
iron,  free  from  sesquichloride,  added,  and  afterwards 
some  hydrochloric  acid.  Several  bright  weighed  strips 
of  copper  are  then  introduced,  and  the  solution  boiled 
until  the  protochloride  at  first  formed  is  converted  into 
subchloride;  the  copper  is  then  withdrawn,  washed, 
dried,  and  weighed.  The  calculation  is  effected  as  in 
No.  121. 


124.  ANALYSIS  OF  NITRE. 

In  order  to  determine  the  amount  of  moisture  in 
crude  nitre,  from  5  to  10  grms.  of  the  specimen,  pre- 
viously reduced  to  powder  and  dried  by  exposure  to 
air,  are  heated  to  about  150°. 

The  determination  of  the  quantities  of  the  foreign 
salts  present  in  the  specimen,  such  as  sulphates  and 
chlorides,  lime  and  magnesia,  by  the  ordinary  methods, 
would  occupy  too  much  time ;  it  would  be  preferable 
to  estimate  them  by  means  of  standard  solutions  of  the 
reagents,  i.  e.,  by  measuring  the  quantities  of  the  latter 
required  to  effect  complete  precipitation. 

The  appearance  of  the  fracture  is  regarded  as  an 
indication  of  the  quality  of  the  nitre ;  in  pure  nitre, 
the  fracture  is  lustrous,  and  exhibits  a  well-defined 
crystalline  appearance;  but  if  not  more  than  2  per 
cent,  of  common  salt  be  present,  it  is  granular  and 
dull.  An  admixture  of  nitrate  of  soda  (Chili  salt- 
petre) has  the  same  effect. 

Another  method,  which  is  likewise,  however,  inac- 


ANALYSIS  OF   NITRE.  253 

curate,  but  is  most  readily  applied  in  practice,  depends 
upon  the  circumstance  that  a  solution  of  pure  nitre,  at 
the  temperature  at  which  it  is  saturated,  is  still  capa- 
ble of  dissolving  other  salts,  especially  chloride  of 
sodium.  400  grms.  of  the  powdered  specimen  are 
shaken  with  500  cub.  cents,  of  a  solution  of  pure 
nitre;  the  salt  is  then  filtered  off,  again  washed  with 
250  cub.  cents,  of  a  saturated  solution  of  nitre,  dried 
at  100°,  and  weighed.  The  loss  of  weight  expresses 
the  amount  of  the  foreign  salts.  Since  this  process  is 
liable  to  error  from  many  causes,  and  gives  the  amount 
of  pure  nitre,  on  an  average,  2  per  cent,  too  high, 
these  2  per  cent,  must  not  be  neglected  in  calculating 
the  amount  of  impurity  present. 

The  following  process  is  more  accurate,  which  con- 
sists in  converting  the  nitre  contained  in  any  specimen 
into  carbonate  of  potassa,  the  amount  of  which  is  then 
determined  by  means  of  the  standard  acid,  as  in  testing 
potashes. 

9.475  grms,  of  pure  nitre  furnish  a  quantity  of  car- 
bonate potassa,  which  is  capable  of  saturating  100 
measures  of  the  acid  mentioned  in  the  testing  of  pot- 
ashes ;  so  that  if  this  amount  of  impure  nitre  be  em- 
ployed, the  number  of  measures  of  acid  indicate  at 
once  the  percentage  of  pure  nitrate  of  potassa  in  the 
specimen. 

One-fourth  of  the  above  quantity  (2.369  grms.)  of 
the  crude  nitre  is  weighed  out,  intimately  mixed  with 
1  grm.  of  ignited  lamp-black,  or  finely  pulverized 
graphite,*  and  with  12  grms.  of  ignited  and  finely-pow- 
dered common  salt,  which  serves  to  moderate  the  vio- 

*  If  common  coal  is  used  cyanide  of  potassium  and  cyanate  of 
potassa  may  be  formed.  Pure  graphite  may  be  prepared  by  mix- 
ing Ceylon  graphite  with  ^  of  chlorate  of  potassa  to  which  con- 
centrated sulphuric  acid  is  added,  and  then  warmed  until  no  acid 
fumes  are  given  off.  The  mass  is  then  shaken  with  water,  the 
graphite  washed  and  ignited. 

22 


254  GUNPOWDEK. 

lence  of  the  combustion.  The  mixture  is  introduced 
into  a  platinum  crucible,  and  heated  to  redness  over  a 
large  spirit-lamp  or  gas-burner.  Near  the  close  of 
the  operation  a  little  chlorate  of  potassa  is  scattered  in 
the  crucible  in  case  the  saltpetre  happens  to  contain 
any  sulphates.  When  cool,  it  is  dissolved  in  water, 
and  the  standard  acid  added  in  the  manner  directed 
for  testing  samples  of  potashes.  The  number  of  mea- 
sures of  acid  employed  is  multiplied  by  4,  in  order 
to  obtain  the  percentage  of  pure  nitre  in  the  specimen. 

In  following  this  method  it  is  impossible  to  deter- 
mine the  weight  of  the  expelled  carbonic  acid  by 
means  of  the  apparatus  generally  employed  for  this 
purpose,  on  account  of  the  large  quantity  of  common 
salt  which  has  been  added. 

The  simplest  method  for  the  analysis  of  nitre  con- 
sists in  fusing  the  weighed  quantity  of  nitre  with  twice 
its  weight  of  fused  bichromate  of  potassa,  until  all  the 
nitric  acid  is  driven  off.  The  loss  in  weight  shows 
the  quantity  and  also  amount  of  pure  nitrate  of  potassa. 


125.  GUNPOWDER. 

I.  For  the  estimation  of  moisture,  5  or  6  grms.  of 
powder  are  dried  over  sulphuric  acid,  or  in  the  air- 
bath  at  100°. 

II.  A  similar  quantity  of  powder  is  moistened  with 
water,  triturated  in  a  mortar,  rinsed  into  a  filter,  and 
thoroughly  washed.     The  solution  of  nitre  thus  ob- 
tained is  evaporated  to  dryness  in  a  small  weighed 
porcelain  dish,  the  dry  residue  heated  for  some  time 
to  200°,  or  even  till  the  nitre  fuses,  and  its  weight 
determined. 

III.  In  order  to  determine  the  sulphur,  5  grms.  of 
powder  are  intimately  mixed  with  5  grms.  of  anhydrous 


HYDROCYANIC  ACID.  255 

carbonate  of  soda,  5  grms.  of  nitre,  and  20  grms. 
of  decrepitated  chloride  of  sodium,  and  the  mixture 
heated  to  redness  in  a  platinum  crucible.  When  cool, 
the  mass  is  dissolved  in  water,  the  solution  slightly 
acidified  with  nitric  acid,  and  the  sulphuric  acid  pre- 
cipitated by  chloride  of  barium.  (See  No.  3.) 

The  amount  of  carbon  may  be  inferred  by  differ- 
ence. In  order  to  determine  its  quality,  and  to  ascer- 
tain whether  it  has  been  completely  or  incompletely 
carbonized,  the  mixture  of  sulphur  and  carbon  is 
boiled  with  a  solution  of  protosulphide  of  potassium, 
which  dissolves  the  sulphur,  leaving  the  carbon,  which 
must  be  well  washed  and  dried.  The  sulphide  of 
potassium  should  not  contain  any  free  potassa,  since 
this  might  dissolve  an  imperfectly  carbonized  char- 
coal.— Bisulphide  of  carbon  may  also  be  employed  for 
the  extraction  of  the  sulphur. 

The  sulphur  as  well  as  the  coal  may  be  completely 
oxidized  by  boiling  with  a  solution  of  permanganate 
of  potassa.  The  oxide  of  manganese  is  after  wards,  dis- 
solved by  hydrochloric  acid,  and  the  sulphuric  acid 
precipitated  by  chloride  of  barium. 


126.  HYDROCYANIC  ACID. 

In  order  to  determine  the  strength  of  a  solution  of 
pure  hydrocyanic  acid,  a  weighed  quantity  of  it  is 
treated  with  solution  of  nitrate  of  silver,  which  is 
added  gradually,  and  with  frequent  agitation,  until  no 
further  precipitation  takes  place,  and  the  odor  of 
hydrocyanic  acid  has  entirely  disappeared. 

The  precipitated  cyanide  of  silver  is  collected  upon 
a  filter  (previously  dried  at  120°  and  weighed),  washed, 
dried  at  120°,  and  its  weight  determined. 

For  the  estimation  of  the  amount  of  hydrocyanic 
acid  in  the  aqua  amygdalarum  amararum  and  aqua 


256  HYDROCYANIC  ACID. 

faurocerasi,  they  must  first  be  mixed  with  ammonia, 
then  with  nitrate  of  silver,  and  lastly  with  nitric  acid. 

If  hydrochloric  acid  be  contained  in  the  solution, 
together  with  hydrocyanic  acid,  they  are  both  precipi- 
tated from  a  weighed  portion  of  the  solution  by  nitrate 
of  silver,  and  the  precipitate  weighed  upon  a  filter 
dried  at  120°.  Another  weighed  portion  of  the  solution 
is  mixed  with  solution  of  borax  and  evaporated  to 
perfect  dryness.  In  this  way,  all  the  hydrocyanic  acid 
is  volatilized,  and  the  hydrochloric  acid  converted  into 
chloride  of  sodium.  The  dry  residue  is  dissolved  in 
water,  the  solution  acidulated  with  nitric  acid,  and  the 
chlorine  precipitated  by  nitrate  of  silver. 

Another  method,  which  may  be  executed  with  great 
rapidity,  and  suffices  for  the  determination  of  the  hydro- 
cyanic acid  in  any  solution,  whether  bitter  almond- 
water  or  laurel-water,  &c.,  or  for  ascertaining  the  quan- 
tity of  cyanogen  in  crude  cyanide  of  potassium,  depends 
upon  the  circumstance  that  1  equiv.  of  cyanide  of 
potassium  forms,  with  1  equiv.  of  cyanide  of  silver,  a 
soluble  compound  which  is  not  decomposed  by  an  ex- 
cess of  alkali,  but  from  which  nitrate  of  silver  precipi- 
tates the  cyanide,  or  if  a  little  solution  of  chloride  of 
sodium  be  previously  added,  the  chloride  of  silver. 
The  weighed  solution,  containing  hydrocyanic  acid  is 
mixed  with  solution  of  potassa  till  it  has  a  strongly 
alkaline  reaction,  and  a  standard  solution  of  silver  is 
then  added  till  a  permanent  precipitate  begins  to  ap- 
pear. 1  equiv.  of  silver  employed  in  the  standard 
solution  corresponds  exactly  to  2  equivs.  of  hydro- 
cyanic acid. 

Ten  grms.  of  pure  silver  are  dissolved  in  nitric  acid, 
the  solution  evaporated  to  perfect  dryness,  and  diluted 
with  so  much  water,  that  the  whole  solution  may 
occupy  1000  cub.  cents.  100  cub.  cents,  of  this  solu- 
tion, which  contain  therefore  1  grm.  of  silver,  repre- 


FERROCYANIDE   OF   POTASSIUM.  257 

sent  0.5  grm.  of  anhydrous  hydrocyanic  acid,  or  0.481 
cyanogen,  or  1.206  of  cyanide  of  potassium. 


127.  FERROCYANIDE  OF  POTASSIUM. 

2  K  Cy -f-Fe  Cy +  8  HO=K2  Cfy  +  3  HO. 

The  water  is  determined  by  heating  the  finely-pow- 
dered salt  for  some  time  to  about  200°. 

The  cyanogen  can  be  directly  determined  only  by 
an  organic  analysis,  i.  e.,  by  a  combustion. 

For  the  determination  of  the  amount  of  iron,  the 
salt  is  intimately  mixed  with  1J  parts  of  nitre,  and  as 
much  carbonate  of  soda,  and  the  mixture  gradually 
heated  to  redness  in  a  platinum  crucible.  On  dissolving 
the  fused  mass  in  water,  the  iron  remains  behind  in 
the  form  of  sesquioxide,  which  is  washed,  ignited,  and 
weighed.  Since  it  is  liable  to  contain  a  small  amount 
of  alkali,  it  should  be  dissolved  in  hydrochloric  acid, 
reprecipitated  by  ammonia,  washed  and  ignited. 

In  order  to  determine  the  potassium  and  iron,  the 
salt  is  dissolved  in  water,  and  the  solution  precipitated 
by  acetate  of  lead.  The  precipitate  of  ferrocyanide  of 
lead  is  filtered  off*  and  washed. 

From  the  solution,  which  contains  all  the  potassium 
as  acetate  of  potassa,  the  excess  of  lead  is  precipitated 
by  sulphuretted  hydrogen  or  sulphide  of  ammonium, 
the  filtered  solution  evaporated,  the  residue  ignited, 
the  carbonate  of  potassa  converted,  by  hydrochloric 
acid,  into  chloride  of  potassium,  and  weighed  in  that 
form,  after  gentle  ignition.  The  ferrocyanide  of  lead 
is  decomposed  by  digestion  with  sulphide  of  ammonium, 
the  solution  of  ferrocyanide  of  ammonium  filtered  off, 


258  EXAMINATION   FOR   ARSENIC 

evaporated,  and  the  residual  mass  ignited,  with  access 
of  air,  until  only  pure  sesquioxide  of  iron  is  left. 

Ferrocyanide  of  potassium  may  probably  also  be 
decomposed  by  beating  with  bisulphate  of  ammonia. 
The  residue  after  ignition  would  then  consist  of  a 
mixture  of  sesquioxide  of  iron  and  sulphate  of  potassa, 
from  which  the  latter  might  be  extracted  with  water. 
Or,  to  insure  an  accurate  result,  the  ignited  residue 
might  be  dissolved  in  hydrochloric  acid,  the  sesqui- 
oxide of  iron  precipitated  by  ammonia,  the  solution 
evaporated,  and  the  residual  sulphate  of  potassa  ig- 
nited and  weighed. 


128.  EXAMINATION  FOR  ARSENIC  IN  CASES  OF 
POISONING. 

When  poisoning  by  arsenic  is  suspected,  the  poison 
must  be  sought  in  the  contents  of  the  stomach  and  in- 
testines, in  the  substance  of  these  organs  even,  and  in 
other  entire  organs,  as  the  liver,  spleen,  and  lungs;  an 
examination  must  also  be  made  of  the  vomited  matters, 
and  of  the  surrounding  objects,  upon  which  these  may 
have  fallen ;  the  urine  and  faeces  should  also  be  tested 
for  arsenic.  The  nature  of  the  case  will  decide  in 
which  particular  direction  the  arsenic  is  to  be  looked 
for.  It  may  also  sometimes  be  necessary  to  examine 
the  remaining  portions  of  suspected  food,  or  the  ves- 
sels, in  which  the  food  has  been  contained,  or  even  the 
vessel  or  paper  which  may  have  been  used  to  contain 
the  arsenic.  When  the  body  has  been  long  interred, 
and  is  far  advanced  in  putrefaction,  and  the  wood  of 
the  coffin  has  rotted  away,  it  becomes  necessary  to  test 
the  surrounding  earth  for  arsenic  which  may  have 
been  derived  from  the  body. 

The  chemical  investigation  must  be  preceded  by  a 


IN   CASES   OF   POISONING.  259 

very  careful  examination  of  the  contents  of  the  stomach 
and  intestines,  or  of  the  vomited  matters.  The  sub- 
stances to  be  examined  are  spread  out  in  new  and  clean 
porcelain  dishes,  turned  over  with  perfectly  clean  glass 
rods  or  spatulas,  and  examined  with  the  help  of  a  lens. 
The  analyst  should  seek  especially  for  small  white 
hard  particles  or  grains  of  undissolved  arsenious  acid, 
which  may  be  carefully  picked  out  with  a  pair  of  pin- 
cers. These  must  be  looked  for  especially  in  the  folds 
of  the  mucous  coat  of  the  stomach  and  intestines.  By 
stirring  up  the  contents  with  distilled  water,  or  better, 
with  spirit,  and  pouring  off  the  lighter  organic  mat- 
ters, it  is  often  possible  to  separate  a  considerable 
quantity  of  the  heavy  arsenic-powder. 

In  a  judicial  investigation  of  this  description,  the 
aim  of  all  chemical  operations  is  to  obtain  the  arsenic 
in  its  elementary  solid  state,  as  the  so-called  metallic 
arsenic.  In  this  form  alone  it  is  possessed  of  such  highly 
characteristic  properties  as  to  render  it  impossible  to 
confound  it  with  any  other  substance,  and  to  allow  it 
to  be  distinctly  recognized  even  when  in  almost  impon- 
derable quantities.  Moreover,  all  evidence  of  its  pre- 
sence is  insufficient,  unless  it  can  be  laid  before  the 
tribunal  in  this  form  ;  and  all  other  forms  and  states  of 
combination  must  be  considered  as  affording  inconclu- 
sive testimony  as  to  the  existence  of  arsenic  in  the 
substance  under  examination.  This  preparation  or 
isolation  of  arsenic  in  its  metallic  state,  even  in  the 
smallest,  almost  imponderable  quantities,  is  very  sim- 
ple and  easy.  Great  difficulties,  however,  present 
themselves,  when  it  is  necessary  to  extract  these  traces 
of  arsenic,  which  are  diffused  through  a  whole  body, 
from  the  great  mass  of  organic  matter,  and  to  convert 
them  into  some  form  of  combination,  from  which  the 
arsenic  can  be  extracted  in  the  metallic  state. 

It  is  most  convenient,  in  considering  the  process 


260  EXAMINATION   FOE  AKSENIC 

employed  for   the   chemical   examination,  to  regard 
three  different  cases  as  possible : — 

I.  The  arsenious  acid  is  found  in  the  solid  state  in 
the  contents  of  the  stomach  and  intestines,  or  in  the 
vomited  matters. 

II.  The  poison  is  intimately  and  invisibly  mixed 
with,  or  dissolved  in,  the  contents,  &c.,  and  can  there- 
fore no  longer  be  found,  or  separated  by  mechanical 
means,  in  the  solid  state. 

III.  The  stomach  and  intestines  are  empty  or  no 
arsenic  can  be  detected  in  them,  since  it  has  already 
been  absorbed  into  the  mass  of  the  blood,  or  into  the 
substance  of  the  different  organs. 

I.  The  arsenic  is  still  to  be  found  in  the  solid  state, 
and  may  be  picked  out  or  separated  by  levigation  from 
the  contents  of  the  stomach,  &c.*  This  case  is  the 
easiest  of  the  three,  since  it  is  only  to  be  proved  that 
the  substance  found  is  really  arsenic.  This  may  be 
known  by  the  grains  or  particles  exhibiting  the  follow- 
ing characters,  after  having  been  properly  freed  from 
organic  matter : — 

1.  The  particles  are  generally  milk-white,  more  rarely 
clear  and  semi-transparent,  hard,  and  brittle. 

2.  A  particle  of  arsenious  acid,  however  small,  when 
introduced  into  a  small  tube  closed  at  one  end,  and 
heated  in  the  edge  of  the  spirit-flame,  volatilizes  and 
recondenses  farther  up  the  tube,  in  the  form  of  a  white 
sublimate  which  may  be  seen,  especially  when  exam- 
ined with  a  lens,  by  sunlight,  to  consist  of  very  lus- 
trous octohedral  crystals. 

3.  A  small  fragment  placed  upon  red-hot  charcoal, 
is  volatilized,  emitting  a  powerful  odor  of  garlic  (on 
red-hot  glass  or  porcelain  it  volatilizes  without  garlic 
odor,  because  it  is  not  reduced  to  the  state  of  metal). 

*  Poisoning  sometimes  happens  from  commercial  metallic  arse- 
nic (fly-poison,  cobalt,  &c.)«  Brownish-black  grains  or  particles 
should  then  be  looked  for,  which  are  easily  recognized  as  arsenic. 


IN   OASES   OF   POISONING.  261 

4.  A  particle  of  the  substance  is  placed  in  the  end 
of  a  very  narrow  tube  (Fig.  40),  and  above  it  several 

Fig.  40. 


splinters  of  freshly-ignited  charcoal  so  that  they  may 
occupy  about  J  inch  of  the  tube.  This  part  of  the 
tube  is  now  held  horizontally,  in  the  flame  of  the  spirit- 
larnp,  in  such  a  manner  that  the  spot  where  the  arse- 
nious  acid  is  placed  may  remain  without  the  flame. 
When  the  charcoal  is  heated  to  redness,  that  portion 
of  the  tube  is  also  brought  into  the  flame  when  the 
volatilized  arsenious  acid,  passing  over  the  red-hot 
charcoal,  is  reduced,  and  the  metallic  arsenic  deposited 
beyond  the  charcoal,  in  the  form  of  a  dark,  lustrous, 
metallic  ring.  By  a  gent]e  heat,  this  metallic  incrus- 
tation may  be  carried  still  farther  up  the  tube.  If 
the  incrustation  be  chased  hither  and  thither  in  the 
tube  it  is  oxidized,  or  at  least  partly,  and  converted 
into  small  shining,  colorless,  volatile  crystals  of  arse- 
nious acid.  If  the  tube  be  cut  off,  just  before  the  part 
which  contains  the  metallic  ring,  and  the  latter  then 
gently  heated,  the  characteristic  garlic  odor  of  arsenic 
may  be  perceived  on  approaching  the  nose  to  the  ori- 
fice of  the  tube. 

5.  This  reduction  of  arsenic  to  the  metallic  state 
may  be  effected  with  greater  ease  and  certainty  by 
dissolving  a  small  quantity  of  the  substance  in  water 
containing  hydrochloric  acid,  and  testing  the  solution 
in  Marsh's  apparatus,  in  the  manner  to  be  presently 
described  more  particularly. 

6.  A  particle  of  the  arsenious  acid  is  heated  in  a 
small  glass  tube,  closed  at  one  end,  with  a  piece  of  dry 


262  EXAMINATION   FOR  ARSENIC 

acetate  of  potassa  about  as  large  as  a  pin's  head,  when 
the  indescribably  offensive  and  characteristic  odor  of 
kakodyl  should  be  evolved. 

7.  One  or  more  fragments  are  finely  powdered, 
under  distilled  water,  the  powder  rinsed  into  a  small 
beaker-glass  with  20  or  30  drops  of  water,  and  the 
mixture  heated  nearly  to  ebullition  until  the  powder 
is  dissolved.  A  part  of  this  solution  is  mixed,  in  a 
small  test-tube,  with  several  drops  of  solution  of  nitrate 
of  silver,  and  afterwards  with  very  dilute  ammonia, 
added  drop  by  drop.  In  this  way,  if  the  substance 
were  arsenious  acid,  a  considerable  bright  yellow  pre- 
cipitate of  arsenite  of  silver  will  be  produced. — An- 
other portion  of  the  liquid,  mixed  with  several  drops 
of  a  clear  solution  of  ammonio-sulphate  of  copper, 
gives  a  fine  yellowish- green  precipitate  of  arsenite  of 
copper.  A  third  quantity  of  the  solution,  mixed  with 
a  few  drops  of  hydrochloric  acid,  and  afterwards  with 
several  times  its  volume  of  sulphuretted-hydrogen- 
water,  gives  a  bright  yellow  precipitate  of  tersulphide 
of  arsenic,  which  redissolves  perfectly  on  adding  am- 
monia. 

Of  all  these  reactions,  the  reduction  to  the  metallic 
state  in  Nos.  4  and  5  is  the  most  necessary,  because  it 
is  most  characteristic  and  conclusive.  The  others  are 
to  be  viewed  rather  in  the  light  of  superfluous  confir- 
mations, and  are  only  employed  when  a  considerable 
quantity  of  substance  is  at  the  analyst's  disposal. 

II.  Arsenic  can  no  longer  be  perceived  by  the  eye, 
or  mechanically  separated,  in  the  solid  state,  but  is 
contained  in  a  state  of  solution,  or  of  intimate  mixture, 
in  the  contents  of  the  stomach,  &c.  In  this  case, 
which  is  more  difficult  and  of  more  frequent  occur- 
rence than  the  preceding,  the  problem  consists  in  dis- 
solving and  destroying,  by  appropriate  reagents,  the 
whole  mass  of  the  organic  matter  composing  the  con- 
tents, the  vomited  matters,  the  food,  and  even  the 


IN   CASES   OF  POISONING.  263 

stomach  and  intestines  themselves.  This  is  always 
necessary  before  the  arsenic  can  be  detected  with  cer- 
tainty. 

It  is  indispensably  necessary  that  this  operation 
should  be  preceded  by  a  most  careful  examination  of 
the  reagents  to  be  employed,  in  order  to  ascertain 
whether  they  contain,  as  is  not  unfrequently  the  case, 
a  small  quantity  of  arsenic.  This  is  equally  requisite 
whether  the  reagents  have  been  purchased  or  have 
been  prepared  by  the  analyst  himself.  The  distilled 
sulphuric  acid,  the  hydrochloric  acid,  and  the  zinc 
must  especially  be  examined.  This  is  most  conveni- 
ently effected  in  Marsh's  apparatus,  which  will  be  pre- 
sently described,  and  which  is  invaluable  as  allowing 
the  reagents,  which  are  employed  in  it,  to  be  so  readily 
and  surely  tested.  "Without  such  previous  proof  of 
the  absence  of  arsenic  in  the  reagents,  upon  which  the 
chemist  must  lay  great  stress  in  his  depositions,  the 
detection  of  arsenic  in  investigations  of  this  descrip- 
tion cannot  be  brought  forward  in  evidence,  since  it 
might  have  been  derived  from  the  reagents  employed. 
It  should  farther  be  observed  and  stated  in  evidence, 
that  the  investigation  was  conducted  with  new  utensils 
and  vessels  which  had  not  been  used  before ;  and  it  is 
advisable,  moreover,  to  insure  perfect  satisfaction,  that 
it  should  not  be  carried  out  in  an  ordinary  chemical 
laboratory,  or,  at  all  events,  that  the  laboratory  should 
be  well  cleared  before  the  judicial  inquiry  is  entered 
upon. 

If  arsenic  should  be  found  in  an  examination  con- 
ducted with  all  these  precautions  it  is  still  necessary 
to  reflect  that  it  might  occur  in  the  body  quite  acci- 
dentally ;  especially  after  the  administration  of  certain 
medicinal  remedies,  such  as  the  antimonial  compounds, 
preparations  of  phosphorus,  phosphoric,  sulphuric, 
and  hydrochloric  acids,  which  may  contain  arsenic 
from  carelessness  in  their  preparation.  Even  the  hy- 


264  EXAMINATION  FOR  ARSENIC 

drated  sesquioxide  of  iron,  administered  as  an  antidote 
in  a  suspected  case  of  poisoning,  might  have  contained 
arsenic,  unless  prepared  with  great  care.  Or  the 
arsenic  may  have  been  administered  as  a  remedy 
(especially  as  a  secret  medicine).  When  bodies  have 
been  exhumed,  it  becomes  necessary  to  test  the  earth 
with  which  the  coffin  has  been  in  contact,  since  it 
sometimes  happens  that  soils,  especially  such  as  are 
ferruginous,  contain  appreciable  quantities  of  arsenic, 
which  might  have  entered  into  the  body. 

Various  methods  are  employed  for  the  modification 
or  destruction  of  the  organic  matters,  with  a  view  to 
the  extraction  of  the  arsenic. 

1.  When  the  substance  is  in  the  form  of  a  paste,  as 
in  the   contents   of  the   stomach   and    in  the  faeces, 
chlorine-gas  is  passed  to  saturation.     The  chlorine  is 
prepared  by  means  of  sulphuric  acid  and  manganese, 
which  have  been  previously  tested,  and  is  washed  by 
passing  through  a  small  but  high  column  of  water. 
In  order  to  assist  the  action,  the  mass  may,  at  the  same 
time,  be  gently  heated.     Lastly,  when  it  is  completely 
saturated  with  gas,  coagulated,  and  bleached,  the  mix- 
ture is  heated  nearly  to  ebullition  to  expel  the  excess 
of  chlorine,  and  the  solution,  which  must  contain  the 
arsenic,  is  filtered  through  paper  free  from  smalt. 

2.  The  stomach  and  intestines,  with  their  contents, 
are  cut  into  fine  shreds,  placed  in  a  porcelain  dish,  and 
the  whole  mass  uniformly  mixed.     About  J  is  then 
set  aside  in  a  clean  covered  glass,  in  case  any  accident 
should  happen  to  the  remainder.     The  mass  is  then 
treated   with   a   moderately  concentrated   solution  of 
potassa,  and  heat  applied  until  it  is  entirely  or  almost 
entirely  dissolved.     Only  a  small  quantity  of  potassa 
is  necessary  for  this  purpose,  and  the  potassa  should 
therefore  be  gradually  added  to  the  mixture,  so  as  to 
avoid  an  excess,  which  would  interfere  with  the  sub- 
sequent operations.    The  solution  is  afterwards  slightly 


IN  CASES   OF  POISONING.  265 

acidified  with  dilute  sulphuric  acid,  and  chlorine-gas 
is  passed,  to  saturation,  into  the  mass  thus  coagulated, 
as  in  1. 

3.  The  organic  matter  cut  into  shreds,  is  treated 
with  about  as  much  pure  concentrated  hydrochloric 
acid  as  is  equal  to  the  weight  of  the  dry  substances 
contained  in  the  mass ;  enough  water  is  then  added  to 
form  a  thin  paste.  The  dish  is  heated  on  a  water- 
bath,  the  contents  stirred  every  five  minutes,  and  about 
30  grs.  of  chlorate  of  potassa  (free  from  lead)  added  to 
the  hot  liquid  until  it  has  become  clear  yellow,  homo- 
geneous, and  limpid.  After  being  heated  for  some 
time  longer,  the  solution  is  strained  through  a  moist- 
ened filter  of  white  paper,  free  from  smalt,  the  residue 
washed  upon  the  filter  with  hot  water  till  the  washings 
are  no  longer  acid,  the  whole  liquid  poured  together 
into  a  porcelain  dish,  and  evaporated  to  about  1  pound 
upon  the  water-bath. 

The  solution  obtajned  by  one  of  these  methods  is 
poured  into  a  cylindrical  glass  or  into  a  flask,  and  a 
slow  stream  of  sulphuretted  hydrogen  gas  passed  into 
it  to  complete  saturation.  All  the  arsenic  is  thus  pre- 
cipitated as  sulphide,  Its  precipitation  is  much  pro- 
moted if  the  liquid  be  heated  for  about  half  an  hour  to 
50°  or  60°,  while  the  gas  is  passing,  and  allowed  to 
cool  before  the  stream  of  gas  is  discontinued.  When 
saturated,  the  liquid  is  allowed  to  remain  for  twenty- 
four  hours  in  a  closed  vessel.  The  precipitate  which 
is  then  deposited  has  generally,  even  if  much  arsenic 
be  present,  a  dirty,  undecided,  grayish-brown  color.* 
The  greater  portion  of  the  solution  is  poured  off,  and 
the  precipitate  thrown  upon  the  smallest  possible  filter 
of  Swedish  paper;  free  from  smalt,  upon  which  it  is 

_*  If  lead,  copper,  mercury,  or  antimony  were  present,  the  preci- 
pitate would  also  contain  the  sulphides  of  these  metals,  for  which 
it  would  have  to  be  particularly  examined. 

23 


266  EXAMINATION    FOB  ARSENIC 

well  washed.  The  filtrate,  before  being  thrown  away, 
should,  for  greater  certainty,  again  be  saturated  with 
sulphuretted  hydrogen  gas  and  set  aside  for  some  time 
in  a  closed  vessel. 

This  precipitate  always  contains,  in  addition  to  sul- 
phide of  arsenic,  certain  sulphuretted  organic  matters 
which  are  precipitated  with  it,  and  must  be  completely 
destroyed;  this  is  best  effected  in  the  following  man- 
ner:— 

The  filter  containing  the  precipitate  is  placed  in  a 
somewhat  capacious  crucible  of  genuine  porcelain,  and 
digested  with  concentrated  nitric  acid  until  the  whole 
is  converted  into  a  homogeneous  mass.  The  free  ni- 
tric acid,  of  which  more  may  be  added  if  necessary,  is 
neutralized  with  pure  carbonate  of  soda,  and  the  solu- 
tion carefully  evaporated  to  dryness.  It  is  important 
that  the  mass  should  contain  a  sufficient  quantity  of 
nitrate  of  soda,  which  is  easily  insured.  It  is  gradu- 
ally heated  over  a  large  spirit-lamp,  or  gas-burner, 
until  the  salt  fuses ;  it  blackens  at  first,  but  afterwards 
fuses,  quietly  and  without  deflagration,  to  a  clear  color- 
less liquid.  The  whole  of  the  organic  matter  is  now 
burnt,  and  the  arsenic  converted  into  arsenate  of  soda. 

Pure  concentrated  sulphuric  acid  is  then  gradually 
dropped  upon  the  cooled  saline  mass  in  the  crucible, 
and  a  gentle  heat  applied,  until,  after  addition  of  an 
excess  of  acid,  the  nitric  and  nitrous  acids  are  com- 
2>letely  expelled,  and  the  mass  is  converted  into  bisul- 
phate  of  soda.  If  nitric  acid  containing  hydrochloric 
acid  had  been  originally  employed  for  the  oxidation 
of  the  sulphuretted  hydrogen  precipitate,  a  loss  of 
arsenic  might  now  result,  from  its  volatilization  as 
chloride  of  arsenic.  The  purity,  in  this  respect,  of  the 
nitric  acid  and  carbonate  of  soda,  must  therefore  have 
been  previously  ascertained. 

The  acid  saline  mass  is  now  dissolved,  in  the  crucible 
itself,  with  the  smallest  quantity  of  hot  water,  and  the 
solution  introduced  into  Marsh's  apparatus. 


IN  CASES  OF   POISONING.  267 

4.  The  organic  matter  is  introduced,  together  with 
the  whole  of  the  liquid,  into  a  capacious  tubulated 
retort,  and  about  an  equal  weight  of  rock-salt,  or  of 
fused  common  salt,  in  small  fragments,  added.  The 
retort  is  connected  with  a  tubulated  receiver,  furnished 
with  a  delivery-tube  which  dips  into  water.  A  quan- 
tity of  (tested)  sulphuric  acid,  sufficient  to  decompose 
the  whole  of  the  chloride  of  sodium,  is  then  poured 
upon  the  mass  through  a  funnel  tube  passed  into  the 
tubulure  of  the  retort.  When  the  intumescence  and 
evolution  of  hydrochloric  acid  have  ceased,  the  con- 
tents of  the  retort  are  heated  to  boiling,  the  receiver 
being  kept  thoroiighly  cool.  All  the  arsenic  is  thus 
distilled  off  as  chloride,  especially  towards  the  last,  in 
proportion  as  the  contents  of  the  retort  become  more 
concentrated,  on  which  account  the  distillation  should 
be  carried  pretty  far.  The  arsenic  is  converted  into 
chloride,  even  when  it  exists  in  the  mass,  in  the  form 
of  sulphide.  The  distillate  may  be  at  once  introduced 
into  Marsh's  apparatus.  It  is  safer,  since  some  organic 
matter  might  possibly  have  passed  over,  to  precipitate 
the  arsenic  from  the  solution  by  sulphuretted  hydro- 
gen, and  to  treat  the  precipitate  as  directed  above.  In 
the  same  way  the  small  quantity  of  arsenic  contained 
in  the  water  in  which  the  hydrochloric  acid  was  con- 
densed, may  be  precipitated.  This  method  seems  to 
be  the  most  simple  and  sure,  to  distil  the  mass  directly 
with  concentrated  hydrochloric  acid,  instead  of  salt 
and  sulphuric  acid,  and  the  arsenic  passes  over  as 
chloride. 

Marsh's  apparatus  has  the  following  simple  con- 
struction :  a  is  a  two-necked  bottle  capable  of  holding 
£,  or  at  most  1  pint.  Both  necks  are  fitted  with  new 
perforated  corks,  which  must  be  perfectly  tight. 
Through  one  of  these,  the  funnel  tube  b  is  passed  air- 
tight, and  through  the  other,  the  bent  tube  c,  which  is 
expanded  at  c  into  a  bulb  about  an  inch  in  diameter. 


268  EXAMINATION   FOR   ARSENIC 

This  bulb  serves  to  collect  the  particles  of  liquid  which 
are  thrown  up  from  the  contents  of  the  bottle,  and 

Fig.  41. 


which  drop  down  again  into  the  latter,  from  the  ob- 
liquely cut  end  of  the  tube.  The  other  end  of  this 
tube  is  connected,  by  means  of  a  cork,  with  the  tube 
d,  about  6  inches  long,  which  is  filled  with  fused  pure 
chloride  of  calcium,  free  from  powder,  destined  to  re- 
tain the  moisture.  In  the  opposite  end  of  the  tube  d, 
is  fixed,  air-tight,  another  tube  e,  made  of  glass  free 
from  lead,  12  inches  long,  and  at  most  J-%  inch  in  in- 
ternal diameter.  It  should  be  made  of  rather  thick 
glass,  and  somewhat  drawn  out  at  the  end.  It  must 
be  observed  that  the  funnel-tube  d  is  indispensably 
necessary.  If  a  two-necked  bottle  cannot  be  procured, 
one  with  a  single  neck  must  be  provided  with  a  cork 
bored  with  two  holes.  •>._ . 

A  better  form  of  apparatus  than  the  one  just  de- 
scribed is  shown  in  Fig.  42,  which  differs  from  it  in 
having  the  large  tube  filled  with  asbestus  to  prevent 
impurities  being  carried  over  mechanically  by  the  cur- 
rent of  gas. 

Several  ounces  of  granulated  zinc  are  introduced 


IN   CASES   OF   POISONING.  269 

into  the  bottle,  which  is  then  half-filled  with  distilled 
water :  when  the  apparatus  is  all   arranged,  distilled 

Fig.  42. 


concentrated  sulphuric  acid  is  added  in  small  portions 
by  the  funnel  tube  b,  very  gradually,  so  that  the  mix- 
ture may  not  become  too  hot,  lest  sulphuretted  hydro- 
gen should  be  formed.  The  evolution  of  hydrogen  is 
allowed  to  proceed  until  it  is  judged  that  all  atmos- 
pheric air  is  expelled,  and  that  the  apparatus  is  per- 
fectly filled  with  hydrogen. 

The  narrow  delivery-tube  is  then  heated  to  redness 
at  e,  for  at  least  half  an  hour,  by  a  spirit  lamp  with  a 
double  draught,  or  a  powerful  gas-burner,  the  evolu- 
tion of  hydrogen  being  constantly  maintained  by 
adding  acid  from  time  to  time.  In  this  way,  the  acid 
and  zinc  are  tested  for  any  trace  of  arsenic  which 
might  be  present.  If  they  are  pure,  no  incrustation 
will  be  deposited  at  the  ignited  spot,  e.  If  arsenic  be 
present,  a  metallic  mirror  is  obtained  at  this  portion 
of  the  tube,  and  the  acid  and  zinc  cannot  be  used  ; 
even  the  apparatus  must  then  be  carefully  cleaned,  or, 
better,  replaced  by  a  new  one.  In  the  same  manner 
any  arsenic  might  be  detected  in  the  hydrochloric 
acid,  the  chlorate  of  potassa  (after  having  been  com- 
pletely converted  by  fusion  into  chloride  of  potas- 

23* 


270  EXAMINATION   FOE   ARSENIC 

si  urn),  the  nitre,  and  the  hydrate  of  potassa  (for  the 
third  case),  which  must  first  be  converted  into  sul- 
phate by  adding  sulphuric  acid.  The  quantities  em- 
ployed for  testing  should  not  be  too  small ;  at  least 
an  ounce  of  each  reagent  should  be  taken. 

When  the  reagents  have  been  tested  in  this  manner, 
and  shown  to  be  absolutely  free  from  arsenic,  the 
examination  of  the  substance  may  be  proceeded  with. 
The  solution  to  be  tested,  containing  any  arsenic  which 
may  have  existed  in  the  body,  is  poured  through  the 
funnel  tube  b  into  the  apparatus  filled  with  hydrogen, 
and  from  which  hydrogen  is  being  evolved,  the  tube  e 
being  already  heated  to  redness  at  the  same  spot.  In 
order  that  none  of  the  liquid  may  remain  in  the  tube 
b,  the  latter  is  rinsed  with  about  the  same  quantity  of 
pure  water,  care  being  taken  that  no  air  is  poured  in 
with  it. 

If  arsenic  be  present,  there  will  soon  appear,  in  the 
portion  of  the  tube  e,  beyond  the  heated  spot,  a  dark 
stain,  which  is  at  first  brownish,  and  afterwards  becomes 
lustrous  and  gradually  increases  until,  when  large 
quantities  of  arsenic  are  present,  it  forms  an  opaque 
metallic  mirror.  At  the  same  time  the  gas  issuing 
from  the  tube  e  may  be  kindled,  and  a  dish  of  white 
genuine  porcelain  held  in  the  flame,  which  should  not 
be  too  feeble;  lustrous  black  or  brownish  spots  of 
metallic  arsenic  will  then  be  deposited,  and  a  great 
many  may  sometimes  be  obtained.  When  the  heated 
portion  of  the  tube  is  not  very  long,  more  or  less 
arsenetted  hydrogen  escapes  decomposition  and  fur- 
nishes the  above-mentioned  spots.  No  imitation  of 
porcelain  (stone-ware  or  delf)  should  be  employed  for 
this  purpose,  since  the  glaze  of  these  materials  very 
often  contains  lead,  the  reduction  of  which  might  pro- 
duce dark  spots  even  though  no  arsenic  were  present. 
If  a  large  quantity  of  arsenic  be  contained  in  the  mix- 
ture, so  that  many  thick  arsenic-spots  can  be  obtained, 


IN   CASES   OF   POISONING.  271 

they  may  be  easily  recognized  by  means  of  the  charac- 
teristic reactions  given  above,  after  they  have  been 
dissolved  in  a  few  drops  of  nitric  acid,  and  the  greater 
excess  of  acid  has  been  expelled  by  a  very  gentle  heat. 
If  only  traces  of  arsenic  be  present,  the  spots  are  so 
feeble  that  their  nature  may  remain  uncertain.  The 
only  indication  which  is  perfectly  conclusive,  is  the 
production,  in  the  red-hot  tube,  of  a  metallic  mirror, 
which  must  volatilize  when  gently  heated,  and  re-con- 
dense upon  a  cool  part  of  the  tube,  at  the  same  time 
imparting  to  the  evolved  gas  the  peculiar  garlic  odor. 

When  the  arsenical  mirror  no  longer  increases,  and 
the  flame  ceases  to  deposit  the  spots,  the  operation  is 
discontinued.  It  is  then  very  convenient  to  draw  the 
tube  e  gently  out,  while  it  is  still  red-hot  and  soft,  and 
to  close  it,  when  the  metallic  mirror  is  obtained  in  a 
tube,  which  may  be  sealed  also  at  the  other  end,  and 
laid  before  the  authorities. 

If  the  analyst  have  reason  to  believe  that  a  large 
quantity  of  arsenic  is  present,  it  is  well  not  to  employ 
the  whole  quantity  of  liquid  at  once,  but  to  divide  it 
into  several  portions,  and  to  make  use  of  a  much  lon- 
ger tube  e,  so  as  to  obtain  the  arsenic-mirror  in  several 
places.  The  tube  is  then  cut  with  a  file  into  as  many 
pieces  as  there  are  mirrors  of  arsenic.  That  which 
contains  the  most  characteristic  mirror  is  sealed  at 
both  ends  and  produced  in  court;  the  remaining  mir- 
rors are  subjected  to  the  tests  given  at  p.  260,  among 
which  the  ready  volatility  and  alliaceous  odor  are  the 
most  characteristic  and  decisive. 

If  after  heating  the  tube  for  one  hour,  no  stain  or 
mirror  make  its  appearance,  and  no  traces  of  spots 
have  been  obtained  from  the  flame,  the  absence  of 
arsenic  may  be  inferred,  provided  that  proper  care 
has  been  taken  in  the  former  part  of  the  examination, 
so  that  the  arsenic  cannot  have  been  lost  through  neg- 
ligence or  awkwardness. 


272  EXAMINATION  FOR  ARSENIC 

It  is  very  important,  in  connection  with  this  test 
(Marsh's)  to  remember  that  antimony  also,  whether  as 
teroxide,  or  as  antimonic  acid,  and  especially  when  in 
solution  in  the  form  of  a  salt,  yields  under  the  same 
conditions  as  arsenic,  a  gaseous  antimonetted  hydrogen, 
which  deposits  upon  the  heated  tube,  and  upon  porce- 
lain, a  mirror  and  spots  very  similar  to  those  obtained 
with  arsenic.  This  fact  assumes  so  much  greater  im- 
portance, when  it  is  remembered  that  preparations  of 
antimony,  especially  tartar  emetic,  are  administered  as 
internal  remedies,  so  that,  in  such  cases,  metallic  mir- 
rors are  obtained,  similar  to  those  of  arsenic,  but  con- 
sisting, not  of  that  metal  but  of  antimony.  On  the 
other  hand,  it  must  not  be  forgotten  that  commercial 
arsenic,  as  it  is  employed  for  poisoning,  frequently 
contains  antimony. 

If  the  question  be  merely  whether  a  metallic  mirror 
consist  of  arsenic  or  antimony,  it  may  be  readily  de- 
cided. The  arsenic  may  be  easily  recognized  by  the 
reactions  mentioned  above,  while  the  antimony-mirror 
presents  very  different  characters.  The  antimony- 
mirror  has  a  lighter  color,  and  is  more  lustrous  than 
that  of  arsenic;  the  antimony  spots  are  darker  and  have 
often  a  tinge  of  blue.  Antimony  is  not  nearly  so  easily 
volatilized  as  arsenic,  and  although  both  mirrors  may  be 
chased  from  one  part  of  the  tube  to  another,  there  is  a 
great  difference  in  the  heat  necessary  in  the  two  cases. 
A  very  striking  difference  between  the  two  deposits 
is  seen  in  their  behavior  when  heated ;  the  mirror  of 
antimony,  before  volatilizing,  fuses  into  small  lustrotfs 
globules,  which  may,  in  all  cases,  be  seen  with  the  aid 
of  a  lens;  the  arsenic,  however,  exhibits  no  sign  of 
fusion.  The  most  characteristic  distinction  is  the  pro- 
duction of  the  garlic  odor  when  the  arsenic  is  volatilized 
while  the  antimony  passes  off  in  vapor  without  any 
perceptible  odor.  If  that  portion  of  the  tube  which 
contains  the  mirror  be  heated  while  the  hydrogen  is 


IX  CASES   OF   POISONING.  273 

still  passing,  the  gas  issuing  from  the  orifice  of  the 
tube  will  have  a  distinct  garlic  odor  if  the  deposit 
consist  of  arsenic,  but  will  be  inodorous  if  antimony 
only  be  present.  The  following  reactions  may  also 
be  applied  to  distinguish  arsenic  and  antimony. 

The  arsenical  spots  deposited  upon  porcelain  disap- 
pear when  moistened  with  a  concentrated  alkaline 
solution  of  hypochlorite  of  soda ;  those  of  antimony, 
however,  are  not  affected  by  this  reagent.  If  the  spots 
consist  of  arsenic  and  antimony,  the  latter  not  exceed- 
ing 5  per  cent.,  the  spots  will  also  be  entirely  dissolved. 
Spots  or  mirrors  of  arsenic  disappear  when  moistened 
with  a  drop  of  nitric  acid,  and  gently  warmed,  forming 
a  clear  solution.  If  a  drop  of  nitrate  of  silver  be  added 
to  the  solution,  and  a  glass  rod  moistened  with  caustic 
ammonia  be  held  over  the  liquid,  but  not  allowed  to 
touch  it,  the  mixture  assumes  a  yellow  color,  from  the 
formation  of  a  precipitate  of  arsenite  of  silver.  Some- 
times, if  too  strong  an  acid  or  too  great  a  heat  have 
been  applied,  the  precipitate  consists  of  reddish-brown 
arsenate  of  silver.  This  characteristic  color  is  always 
produced  by  nitrate  of  silver,  when  the  arsenic  spots 
are  dissolved  by  placing  the  capsule  over  a  vessel 
containing  solution  of  chloride  of  lime  and  sulphuric 
acid. 

It  is  true  that  spots  and  mirrors  of  'antimony  also 
disappear  when  treated  with  nitric  acid,  the  antimony, 
however,  is  not  dissolved,  but  merely  converted  into 
white  oxide,  which  gives  no  reaction  with  solution  of 
nitrate  of  silver.  The  antimony  dissolves  in  a  mixture 
of  one  drop  of  nitric  acid  and  one  drop  of  hydrochloric 
acid ;  if  the  greater  excess  of  acid  be  carefully  evapo- 
rated, and  sulphuretted  hydrogen-water  be  dropped 
upon  the  residue,  a  fiery-red  precipitate  of  sulphide  of 
antimony  is  produced.  If  the  spot  had  consisted  of 
arsenic,  a  lemon-yellow  precipitate  would  have  been 
obtained. 

If  the  spots  be  moistened  with  sulphide  of  ammonium 


274  EXAMINATION   FOR   ARSENIC 

and  dried  at  a  very  gentle  heat,  the  arsenic  becomes 
yellow,  the  antimony  orange.  The  yellow  spots  of 
sulphide  of  arsenic  are  not  affected  by  hydrochloric 
acid,  while  those  of  sulphide  of  antimony  disappear  on 
gently  heating. 

If  sulphuretted  hydrogen  gas  be  passed  through  the 
tube  containing  the  metallic  mirror,  and  heat  applied, 
the  metal  is  converted  into  a  sulphide.  If  the  mirror 
consist  of  antimony,  black,  or  partly  orange-red,  sulphide 
of  antimony  is  produced,  while  arsenic  gives  a  yellow 
sulphide.  The  color,  however,  is  not  the  only  distinc- 
tion between  these  compounds,  another  is  afforded  by 
their  unequal  volatility,  sulphide  of  arsenic  being  far 
more  volatile  than  that  of  antimony. 

Moreover,  antimony,  and  arsenic,  in  the  form  of  sul- 
phides, may  be  separated  by  cyanide  of  potassium, 
according  to  the  method  given  in  No.  62. 

The  presence  of  antimony  in  the  precipitated  sul- 
phides may  also  be  ascertained  by  oxidizing  them  as 
directed  at  p.  266.  In  that  case,  the  fused  mass,  before 
treatment  with  sulphuric  acid,  should  be  dissolved  in 
water,  when  the  antimony  would  remain  undissolved 
in  the  form  of  antimonate  of  soda. 

Or  the  precipitate  by  sulphuretted  hydrogen  may 
be  washed  with  a  concentrated  solution  of  carbonate 
of  ammonia,  which  is  poured  over  it  several  times.  The 
sulphide  of  arsenic  is  dissolved  while  the  sulphide  of 
antimony  remains  undissolved.  If  there  is  a  consider- 
able quantity  of  the  precipitate,  a  portion  may  be 
dissolved  in  aqua  regia,  the  solution  treated  with  sul- 
phurous acid  to  reduce  the  arsenic  acid  to  arsenious, 
concentrated  by  evaporation,  a  piece  of  bright  copper  foil 
placed  in  it,  and  then  warmed.  Antimony  and  arsenic 
are  reduced  and  cover  the  copper  with  a  steel-colored 
coating,  which  is  easily  removed  if  the  copper  is  heated 
with  caustic  ammonia.  It  is  then  easily  determined 
which  of  the  metals  is  present.  If  both,  they  may  be 


IN   CASES  OF  POISONING.  275 

separated  by  heating  the  substance  carefully  in  a  slow 
current  of  hydrogen.  All  the  arsenic  will  be  sublimed. 
If  hydrogen  gas  containing  arsenic,  is  passed  into  a 
solution  of  nitrate  of  silver  contained  in  a  Liebig's 
bulb  tube,  it  forms  a  precipitate  of  metallic  silver,  and 
arsenious  acid,  which  is  easily  found  in  the  liquid. 
Antimonetted  hydrogen  forms  in  a  solution  of  silver, 
a  precipitate  of  antimonide  of  silver.  If  a  mixture  of 
arsenetted  and  antimonetted  hydrogen  from  the  Marsh 
apparatus  is  conducted  into  a  solution  of  silver,  a 
mixture  of  antimonide  and  metallic  silver  are  precipi: 
tated.  If  this  precipitate  is  washed  with  hot  water  and 
then  boiled  with  a  concentrated  solution  of  tartaric  acid, 
the  antimony  alone  is  dissolved  and  is  then  easily 
recognized  by  hydrosulphuric  acid  after  acidifying 
with  hydrochloric  acid.  (See  also  No.  61.) 

III.  If  no  arsenic  was  found  in  the  stomach  and 
intestines,  it  must  be  supposed  to  have  been  partly 
carried  away  in  the  vomited  matters  and  faeces,  and 
partly  absorbed  into  the  mass  of  the  blood,  and  into 
those  organs  which  are  rich  in  blood.  In  this  case, 
the  same  process  is  employed  as  in  the  preceding,  the 
arsenic  being  sought,  according  to  the  same  method, 
in  the  liver,  spleen,  lungs,  heart,  and  kidneys.  If  urine 
were  found  in  the  bladder,  or  faecal  matter  in  the  large 
intestines,  they  should  be  examined  first.  The  urine 
must  not  be  introduced  at  once  into  Marsh's  apparatus 
since  the  frothing  to  which  it  gives  rise  would  interfere 
with  the  progress  of  the  experiment ;  the  urine  should 
therefore  be  slightly  acidified,  with  hydrochloric  acid, 
sulphuretted  hydrogen  passed  through  it,  and  the  sub- 
sequent process  conducted  as  in  the  second  case. 

Investigations  of  this  description  are  in  the  highest 
degree  laborious,  troublesome,  and  disgusting,  when 
the  body  to  be  examined  has  been  interred  for  months 
or  years,  and  has  passed  into  a  state  putrefaction.  In 
such  a  case,  it  is  frequently  no  longer  possible  to  dis- 


276  EXAMINATION   FOR  ARSENIC 

tinguish  or  separate  individual  organs,  and  the  analyst 
is  then  necessitated  to  examine  the  whole  mass  of  putre- 
fied organs,  or  the  whole  of  the  soft  parts  which  dry 
up  under  some  particular  local  circumstances,  and  even 
the  bones.  When  this  is  the  case,  the  body  should 
not  be  laid  in  a  bath  of  chlorine- water  or  solution  of 
chloride  of  lime,  in  order  to  destroy  the  offensive  odor, 
since  arsenic  may  thereby  be  extracted  and  lost.  If 
chlorine-gas  be  employed  to  disinfect  the  body,  it  must 
be  evolved  by  means  of  distilled  sulphuric  acid  free 
from  arsenic.  All  the  soft  parts,  especially  those  which 
may  have  formed  parts  of  the  abdominal  viscera,  are 
carefully  separated  from  the  bones,  and  treated  as  in 
the  second  case. 

The  following  is  another  convenient  process  to  be 
especially  preferred  for  the  treatment  of  bodies  which 
have  been  exhumed  entire  after  some  months'  interment. 

The  entire  soft  parts  are  treated  in  a  large  dish  of 
genuine  porcelain,  with  moderately  strong  nitric  acid, 
which  has  been  previously  tested  for  arsenic;  the  dish 
is  then  heated  upon  a  sand-bath,  and  its  contents  well 
stirred,  until  the  organic  matters  are  so  far  destroyed 
and  dissolved  as  to  form  a  homogeneous  pasty  mixture. 
This  is  now  neutralized  with  a  solution  of  pure  hydrate 
or  carbonate  of  potassa,  and  about  as  much  finely- 
powdered  nitre  (previously  tested)  added,  as  is  equal 
in  weight  to  the  soft  parts.  The  whole  is  now  evapo- 
rated to  dryness,  with  constant  stirring,  and  the  dry 
mass  introduced  by  degrees,  in  small  portions,  into  a 
new  clean  Hessian  crucible  heated  to  dull  redness.  In 
this  manner,  the  whole  of  the  organic  matter  is  burnt, 
and  the  arsenic,  if  present,  converted  into  arsenate  of 
potassa.  In  this  process,  it  is  important,  and  not  very 
easy,  to  add  the  proper  quantity  of  nitre.  If  too  little 
nitre  be  employed,  part  of  the  organic  matter  may 
.  remain  unburnt,  and  arsenic  may  be  volatilized  from 
the  carbonaceous  mass ;  on  the  other  hand,  too  much 


IN  CASES  OF   POISONING.  277 

nitre  would  interfere  with  the  subsequent  treatment  of 
the  mass.  It  is  better  to  make  a  preliminary  test  with 
a  small  portion  of  the  mixture,  by  introducing  it  into 
a  small  red-hot  crucible,  and  observing  whether  the 
mass  is  perfectly  white  after  deflagration.  If  it  be 
black  and  carbonaceous,  more  nitre  must  be  added. 

The  mass,  which  now  consists  essentially  of  carbo- 
nate, nitrate,  and  nitrite  of  potassa,  and  may  also  contain 
arsenate  of  potassa,  is  dissolved  in  the  smallest  possible 
quantity  of  boiling  water,  and  the  solution,  without 
filtering  off  from  the  suspended  phosphate  of  lime  and 
silica,  gradually  mixed,  in  a  porcelain  dish,  with  a 
slight  excess  of  sulphuric  acid.  The  pasty  saline  mass 
thus  produced  is  carefully  heated  till  all  the  nitrous 
and  nitric  acids  are  expelled,  a  point  to  which  great 
attention  must  be  paid.  On  cooling,  the  mass  is  stirred 
up  with  a  little  cold  water,  and  the  solution  poured  off 
from  the  large  deposit  of  sulphate  of  potassa.  The 
latter  is  washed  several  times  with  cold  water,  the 
washings  mixed  with  the  first  solution,  and  the  liquid, 
treated  as  above,  with  sulphuretted  hydrogen.  The  pre- 
cipitate then  only  requires  to  be  oxidized  with  nitric 
acid,  with  the  precaution  that  the  acid  must  be  entirely 
removed  by  evaporation  before  the  solution  is  intro- 
duced into  Marsh's  apparatus. 

It  is  rarely  of  importance  to  the  evidence  that  the 
weight  of  arsenic  existing  in  a  body  should  be  deter- 
mined. Such  an  estimation  can  only  be  relative,  since 
it  is  impossible  to  extract  and  weigh  the  whole  of 
the  arsenic  contained  in  all  the  parts  of  a  body.  In 
such  a  case,  a  somewhat  longer  reduction-tube  should 
be  employed,  into  which  is  introduced  a  closely  twisted 
spiral  of  pure  bright  copper,  about  two  inches  in 
length ;  this  spiral  is  accurately  weighed  with  the  tube. 
The  latter  is  then  heated  in  two  places,  one  nearer  the 
evolution-bottle,  for  the  deposition  of  a  mirror;  the 
other,  at  some  distance,  where  the  strip  of  copper  is 
24 


278  EXAMINATION   FOB  PHOSPHORUS. 

placed,  which  combines  with  all  the  remaining  arsenic, 
forming  steel-gray  arsenide  of  copper.  The  increase 
of  weight  of  the  tube  indicates  the  amount  of  arsenic, 
which  is  calculated  as  arsenious  acid. 


129.  EXAMINATION  FOR  PHOSPHORUS  IN  CASES 
OF  POISONING. 

Since  phosphorus  has  been  used  to  poison  mice,  &c., 
and  the  poisonous  action  of  friction  matches  has  become 
extensively  known,  phosphorus  has  not  ^infrequently 
been  resorted  to  as  an  agent  for  causing  death.  It  is 
often  necessary,  therefore,  to  examine  some  article  of 
food,  or  the  contents  of  a  stomach,  for  this  substance. 
It  is  obvious  that,  in  cases  of  the  kind,  his  whole 
attention  must  be  directed  to  the  separation  of  the 
phosphorus  in  ihefree  state,  or  to  producing  such  reac- 
tions as  will  enable  him  to  infer  the  presence  of  free 
phosphorus ;  since  the  mere  finding  of  phosphorus  in 
form  of  phosphates  would  prove  nothing,  as  phosphates 
invariably  form  constituents  of  animal  and  vegetable 
bodies. 

A.  Detection  of  Unoxidized  Phosphorus. 

I.  Test  in  the  first  place  the  suspected  matters  as  to 
whether  free  phosphorus  is  recognizable  by  its  odor  or 
by  its  luminosity  in  the  dark,  exposing,  for  this  pur- 
pose, the  materials  to  the  air,  as  much  as  is  necessary, 
by  rubbing,  stirring,  or  shaking. 

II.  A  portion  of  the  substance  is  placed,  according 
to  the  plan  of  J.  Scherer,  in  a  small  flask;  suspend  in 
it,  above  the  substance,  by  aid  of  the  loosely  fitted  cork, 
a  slip  of  filter  paper  moistened  with  neutral  solution 
of  nitrate  of  silver,  and  warm  the  whole  to  85°  to  105° 


DETECTION  OF   UNOXIDIZED  PHOSPHORUS.       279 

Fah.  In  case  the  paper  is  not  colored  black  after 
some  time,  unoxidized  phosphorus  cannot  be  present, 
and  it  is  then  unnecessary  to  proceed  further  by  the 
methods  III.  and  TV.  The  operator  may  go  on  to  (VL). 
If,  on  the  other  hand,  the  paper  blackens,  this  is  no 
certain  evidence  of  the  presence  of  phosphorus,  because 
various  substances,  viz.,  hydrosulphuric  acid  (detectable 
by  means  of  a  slip  of  paper  moistened  with  solution  of 
lead  or  terchloride  of  antimony),  formic  acid,  products 
of  putrefaction,  &c.,  may  produce  the  same  result. 
Proceed  then  with  the  substance  as  directed  in  III.  and 
IV. 

III.  The  luminosity  of  phosphorus,  of  all  its  charac- 
ters, furnishes  the  most  striking  evidence  of  its  presence 
in  the  free  state.  A  large  sample  of  the  substance  is 
accordingly  examined  by  the  following  well-proved 
and  admirable  method  of  E.  Mitscherlich. 

Mix  the  substance  under  examination  with  water 
and  some  sulphuric  acid,  and  subject  the  mixture  to 
distillation  in  a  flask,  A.  (See  Fig.  43.)  This  flask  is 
connected  with  an  evolution-tube  b,  and  the  latter  again 
with  a  glass  cooling  or  condensing  tube,  c  c  c,  which 
passes  through  a  perforated  cork,  a,  in  the  bottom  of  a 
cylinder,  B,  into  a  glass  vessel,  C.  Cold  water  runs 
from  D,  through  a  stopcock,  into  a  funnel,  i,  which 
extends  to  the  bottom  of  B ;  the  warmed  water  flows 
off  throuh  g* 

Now,  if  the  substance  in  A  contains  phosphorus, 
there  will  appear,  in  the  dark,  in  the  upper  part  of  the 
condensing  tube  at  the  point  r,  where  the  aqueous 
vapors,  distilling  over,  enter  that  part  of  the  tube,  a 
strong  luminosity,  usually  a  luminous  ring.  If  you 
take  for  distillation  5  oz.  of  a  mixture  containing  only 
?!0th  of  a  grain  of  phosphorus,  and  accordingly  only  1 

*  Instead  of  this  vertical  condenser,  an  ordinary  glass  one  used 
for  distillation  may  be  substituted. 


280 


EXAMINATION   FOR   PHOSPHORUS. 


part  of  phosphorus,  in  100,000  parts  of  mixture,  you 
may  distil  over  3  oz.  of  it— which  will  take  at  least  half 
an  hour — without  the  luminosity  ceasing ;  Mitscherlich, 
in  one  of  his  experiments,  stopped  the  distillation  after 

Fig.  43. 


half  an  hour,  allowed  the  flask  to  stand  uncorked  a 
fortnight,  and  then  recommenced  the  distillation  :  the 
luminosity  was  as  strong  as  at  first.  If  the  fluid 
contains  substances  which  prevent  the  luminosity  of 
phosphorus  in  general,  such  as  ether,  alcohol,  or  oil 


DETECTION   OF   UNOXIDIZED   PHOSPHORUS.       281 

of  turpentine,  no  luminosity  is  observed  so  long  as 
these  substances  continue  to  distil  over.  In  the  case 
of  ether  and  alcohol,  however,  this  is  soon  effected, 
and  the  luminosity  accordingly  very  speedily  makes 
its  appearance ;  but  it  is  different  with  oil  of  turpentine 
which  exercises  a  lasting  preventive  influence  upon 
the  manifestation  of  this  reaction. 

a.  After  the  termination  of  the  process,  globules  of 
phosphorus  are  found  at  the  bottom  of  the  receiver, 
C.  Mitscherlich  obtained  from  5  oz.  of  a  mixture  con- 
taining ^  grain  of  phosphorus,  so  many  globules  of 
that  body  that  the  one-tenth  part  of  them  would  have 
been  amply  sufficient  to  demonstrate  its  presence.  In 
medico-legal  investigations  these  globules  should  first 
be  washed  with  alcohol  and  then  weighed.  A  portion 
may  afterwards  be  subjected  to  a  confirmatory  exami- 
nation, to  make  quite  sure  that  they  really  consist  of 
phosphorus :  the  remainder,  together  with  a  portion  of 
the  fluid  which  shows  the  luminosity  upon  distillation, 
should  be  sent  in  with  the  report. 

The  experiment  should  be  made  in  a  perfectly  dark 
room,  best  at  night.  If  it  is  made  in  the  daytime  the 
room  should  be  darkened  by  aid  of  curtains  or  blinds, 
so  that  no  reflections  whatever  from  the  surfaces  of  the 
glass  vessels  or  of  the  fluids  moving  in  them  shall  oc- 
casion mistakes.  It  is  advisable,  even,  especially  when 
very  minute  traces  of  phosphorus  are  searched  for,  to 
pass  the  evolution-tube  through  a  screen,  at  5,  to  pre- 
vent such  reflections  being  occasioned  by  the  light  of 
the  lamp  by  which  the  flask  is  heated. 

The  residue  of  the  distillation  is  further  examined 
according  to  (VI.)  for  phosphorous  acid.  The  distil- 
late, also,  may  be  tested  in  the  same  manner  to  confirm 
the  presence  of  phosphorus,  or  of  phosphorous  acid 
arising  from  its  oxidation. 

IV.  Another  sample  of  the  substance  may  be  exa- 
mined, according  to  experiments  made  by  Neubauer 

24* 


282  EXAMINATION   FOR   PHOSPHORUS. 

and  Fresenius,  in  the  following  manner.  It  is  brought 
into  a  flask  with  doubly-perforated  stopper,  water  is 
added,  if  necessary,  and  dilute  sulphuric  acid  to  aid 
reaction.  Washed  carbonic  acid  gas*  is  now  slowly 
conducted  through  the  mixture  by  means  of  a  glass 
tube  passing  through  the  cork  and  reaching  nearly 
down  to  the  bottom  of  the  flask.  From  a  short  tube 
above  the  current  of  gas  is  led  through  one  or  two 
V-formed  tubes  which  contain  neutral  solution  of  ni- 
trate of  silver.  When  the  flask  is  filled  with  carbonic 
acid  it  is  warmed  in  a  water-bath.  The  experiment  is 
kept  up  for  several  hours.  If  free  phosphorus  be 
present,  a  portion  of  it  volatilizes  unoxidized  in  the 
stream  of  carbonic  acid,  and  on  passing  into  the  silver- 
solution  produces  there  an  insoluble  black  precipitate 
of  phosphide  of  silver,  together  with  phosphoric  acid. 
Since  a  black  insoluble  precipitate  may  be  caused  by 
various  volatile  reducing  agents  or  by  hydrosulphuric 
acid,  its  appearance  is  not  proof  of  the  presence  of 
phosphorus,  though  its  non-formation  demonstrates 
conclusively  that  free  phosphorus  is  absent. 

a.  A  PRECIPITATE  formed  in  the  silver  solution  in 
the  above  experiment  is  collected  on  a  filter  (which 
has  been  previously  washed  with  dilute  nitric  acid  and 
water),  and  is  well  washed  with  water.  The  phosphide 
of  silver,  which  may  be  contained  in  this  precipitate, 
is  detected  by  the  method  of  Blondlot,  improved  by 
Dussard.  a,  Fig.  44,  is  an  apparatus  for  evolving  hy- 
drogen ;  b  is  filled  with  fragments  of  pumice-stone 
drenched  with  concentrated  potassa-lye ;  c  is  a  common 
spring  clamp ;  d  a  clamp  that  can  be  nicely  adjusted 
by  means  of  a  screw  or  wedge ;  e  is  a  platinum  jet 
which  is  kept  cool  by  means  of  moistened  cotton. 
This  platinum  jet  is  essential,  since  the  flame  would 
be  colored  yellow  if  burned  directly  from  a  glass  tube. 

*  The  apparatus,  Fig.  41,  may  be  conveniently  employed. 


DETECTION   OF   UNOXIDIZED   PHOSPHORUS.      283 

At  the  outset  it  is  needful  to  test  the  sulphuric  acid 
and  zinc  to  demonstrate  that  they  yield  hydrogen  free 
from  phosphuretted  hydrogen.  For  this  purpose  allow 
the  gas  to  evolve  until  air  is  displaced  from  the  appa- 

Fig.  44. 


ratus,  then  close  c  until  the  acid  has  been  forced  into/ 
then  close  d,  open  c,  and  lastly  open  d,  cautiously  in- 
flaming the  gas  at  the  jet  and  properly  regulating  its 
issue.  If  the  flame,  when  examined  in  a  rather  dark 
place,  is  colorless,  exhibits  no  trace  of  a  green  cone  in 
its  interior  and  no  emerald-green  tinge  when  a  porce- 
lain dish  is  depressed  into  it,  the  hydrogen  is  pure. 
After  verifying  this  result  by  a  second  trial,  the  preci- 
pitate to  be  examined  is  rinsed  into/,  care  being  taken 
that  it  passes  completely  into  a,  and  the  flame  is  again 
observed  as  before.  In  case  but  a  minimum  of  phos- 
phide of  silver  be  present  the  green  inner  cone  and 


284  EXAMINATION   FOR  PHOSPHORUS. 

emerald-green  coloration  of  the  flame  will  be  percep- 
tible. 

b.  The  SOLUTION  filtered  from  the  silver  precipitate, 
is  freed  from  excess  of  silver  by  hydrochloric  acid, 
filtered  through  a  well  purified  filter,  strongly  concen- 
trated in  a  porcelain  capsule,  and  finally  tested  for 
phosphoric  acid  by  means  of  molybdate  of  ammonia  or 
magnesia  mixture. 

In  this  manner  we  have  most  plainly  detected  the 
phosphorus  of  a  common  match  mixed  with  a  large 
quantity  of  putrefied  blood,  and  in  presence  of  those 
substances  which  prevent  luminosity  in  the  method  of 
Mitscherlich. 

V.  When  enough  phosphorus  is  present  to  weigh, 
its  estimation  is  practicable  by  adopting  Scherer's 
modification  of  the  process  of  Mitscherlich.  The  mass, 
acidified  with  sulphuric  acid,  is  distilled  in  an  atmos- 
phere of  carbonic  acid  gas.  For  this  purpose  it  is  best 
to  fit  into  the  cork  of  the  flask  in  which  the  mixture 
is  distilled,  a  second  tube  through  which  pure  carbonic 
acid  may  be  transmitted  into  the  distilling  apparatus, 
until  it  is  completely  filled,  when  the  stream  of  gas 
may  be  cut  off  and  the  process  continued  as  usual. 
The  receiver  may  consist  of  a  flask  with  a  doubly 
perforated  cork,  the  opening  of  which  passes  over  the 
end  of  the  condensing  tube,  the  other  carrying  a  bent 
glass  tube  which  is  connected  with  a  U  tube  containing 
solution  of  nitrate  of  silver. 

When  the  distillation  is  finished,  globules  of  phos- 
phorus are  found  in  the  receiver,  which,  after  again 
establishing  a  gentle  stream  of  carbonic  acid,  are  united 
by  gently  heating  and  then  are  washed  and  weighed 
as  described  (III.  a.).  The  solution  poured  off  from 
the  globules  is  luminous  in  the  dark,  when  shaken, 
though  not  to  the  same  degree  as  in  Mitscherlich1  s 
process.  The  phosphorus  in  this  liquid  may  be  deter- 
mined, after  oxidation,  by  nitric  acid  or  chlorine,  as 


SILICATES.  285 

phosphoric  acid ;  though,  only,  when  the  operator  is 
certain  that  none  of  the  contents  of  the  distilling  flask, 
which  usually  contain  phosphoric  acid,  have  spirted 
into  the  condenser.  The  entire  quantity  of  phospho- 
rus is  obtained  by  adding  to  that,  thus  determined, 
what  exists  in  the  U  tube.  Its  contents  are  treated 
with  nitric  acid,  the  silver  thrown  down  by  hydrochlo- 
ric acid,  filtered  through  a  washed  filter,  concentrated, 
precipitated  as  phosphate  of  ammonia-magnesia,  and 
weighed  as  phosphate  of  magnesia. 

B.  Detection  of  Phosphorous  Acid. 

VI.  In  case  free  phosphorus  itself  has  not  been 
detected  by  the  above  methods,  it  is  needful  to  look 
for  the  first  product  of  its  oxidation,  viz.,  phosphorous 
acid.  To  this  end  the  residue  of  the  distillation  (II.  a.), 
or  (V.),  or  also  the  residue  of  (IV.)  is  brought  into  the 
apparatus,  Fig.  44,  and  tested  as  described  (IV.  a.)  as 
to  any  green  coloration  of  the  evolved  hydrogen.  If 
the  phosphorous  reaction  appears,  it  is  sufficient ;  other- 
wise organic  matters  may  have  hindered  its  production. 
If,  therefore,  the  flame  is  not  colored,  the  clamp  is 
closed,  and  a  U  tube  containing  neutral  solution  of 
nitrate  of  silver  is  affixed  to  the  apparatus  and  the  gas 
is  allowed  to  stream  slowly  through  the  silver  solution 
for  many  hours.  In  presence  of  phosphorous  acid, 
phosphide  of  silver  is  formed,  which  is  filtered  off  and 
examined  as  directed  in  (IV.  a.). 


130.  SILICATES.* 

A  few  silicates  are  directly  attacked  by  acids,  while 
others  cannot  be  decomposed  by  acids,  except  by  the 
addition  of  a  base,  as,  for  example,  lime. 

*  Methods  of  Sainte-Claire  Deville,  as  given  by  Messrs.  Grandeau 
and  Troost. 


286 


SILICATES. 


By  modifying  the  composition  of  a  silicate,  it  may 
always  be  rendered  decomposable  by  an  acid.  For 
example,  a  silicate  containing  the  following  elements : 

Silica,  Lime, 

Alumina,  Magnesia, 

Iron,  Potassa, 

Manganese,  Soda. 

This  combination  occurs  in  porphyry,  gneiss,  and 
granite. 

In  the  first  place  it  is  necessary  to  observe  the  action 
of  heat  upon  the  silicate,  and  if  there  is  a  loss  in  weight, 
to  determine  its  nature,  whether  it  consists  of  water  or 
fluorine. 

Fig.  45. 


In    most  cases,  the  water   contained    in  a  silicate 
evaporates  at  a  red  heat,  and  it  is  only  necessary  to 


SILICATES.  287 

heat  it  over  a  lamp  fed  by  bellows.  The  water  from 
talcose  minerals  is  only  driven  off  at  a  white  heat. 

This  temperature  may  be  obtained  by  using  the 
lamp  represented  in  Fig.  43.  The  apparatus  is  com- 
posed of  three  principal  pieces:  a  bottle  A  communi- 
cating with  the  tube  E  with  the  reservoir  I  of  spirits 
of  turpentine  or  the  lamp  proper,  which  communi- 
cates by  the  double  tube  G  with  an  apparatus  for  the 
distribution  of  air  forced  by  the  bellows  K,  which 
feeds  at  the  same  time  the  tube  H.* 

Generally  when  minerals  lose  their  volatile  matter, 
only  at  the  temperature  attained  by  the  large  lamp,  it 
is  those  containing  fluorine,  and  it  is  then  necessary 
first  to  examine  the  nature  of  the  volatile  matter. 

The  calcination  is  carried  on  until  neither  water  nor 
fluorine  remains. 

It  should  be  noticed  whether  any  material  is  lost  in 

*  Fig.  46  shows  the  interior  construction  of  the  lamp.  The 
annular  space  0  0  is  closed  on  all  parts,  above  and  at  the  side  by 

Fig.  46. 


a  thick  plate  ;  below  by  a  copper  plate  raised  externally  in  such 
a  manner  as  to  form  a  little  cup  around  the  lamp  in  which  water 
is  poured. 

For  the  management  of  this  lamp  we  refer  to  the  article  by 
M.  H.  Deville,  Annales  de  Chimie  et  de  Physique,  3d  series,  vol. 
xlvi. 


288  SILICATES. 

the  operations  of  calcination  or  not.  The  substance 
is  introduced  in  small  fragments  into  a  weighed  cruci- 
ble, after  which  the  whole  is  weighed,  then  placed 
over  a  gas  lamp  for  several  minutes,  in  order  to  eva- 
porate the  water  and  see  if  there  is  any  loss  indicated 
by  the  balance. 

It  is  heated  -until  the  weight  is  constant,  and  then 
taken  from  the  smaller  lamp  and  placed  over  the  larger 
one,  Fig.  45 ;  at  this  temperature  it  may  be  fused, 
decrepitated,  change  its  color,  all  of  which  should  be 
carefully  noted;  when  it  is  certain  that  the  mineral 
does  not  lose  any  more  in  weight  we  may  proceed  to 
the  analysis. 

The  silicate  is  decomposed  by  the  means  of  lime  ;* 
there  should  be  the  least  possible  amount  of  it  added, 
still,  it  is  necessary  to  employ  such  a  quantity  that  in 
pulverizing  the  glass  obtained  and  treating  it  with 
acids  the  silica  will  take  the  gelatinous  form. 

To  decompose  bottle  glass  it  is  necessary  to  add 
from  10  to  20  per  cent,  of  carbonate  of  lime,  window 
glass  a  little  more  of  it.  Wollastonite,  amphibole,  and 
pyroxenes  35  per  cent,  of  their  weight ;  feldspar  re- 
quires 55  per  cent.,  and  some  substances  containing 
a  large  proportion  of  alumina  and  silica,  as  disthene, 
require  75  per  cent. 

As  a  general  rule  the  quantity  of  lime  to  be  added 
is  in  proportion  to  the  amount  of  silica  contained  in 

*  [To  prepare  it,  white  marble  is  dissolved  in  nitric  acid,  evapo- 
rated to  dryness,  ignited  in  a  platinum  crucible  until  the  nitrate 
begins  to  decompose,  and  caustic  lime  is  formed  on  the  surface. 
It  is  then  treated  with  distilled  water  and  the  thick  liquid  boiled 
for  some  time.  It  is  then  filtered,  and,  when  cold,  an  excess  of 
concentrated  carbonate  of  ammonia  is  added.  This  is  decanted 
and  washed  for  some  time  with  warm  water  over  a  funnel  covered 
with  a  piece  of  cotton  cloth.  If  there  remains  any  nitrate  of  am- 
mouia  in  the  carbonate  of  lime,  it  will  form  nitrate  of  lime  during 
the  desiccation  or  at  the  commencement  of  the  calcination,  and 
the  loss  of  weight  which  is  thus  caused  in  the  carbonate  will  be 
an  error.] 


SILICATES.  289 

the  substance  to  be  analyzed ;  the  maximum  should 
correspond  to  the  pure  silica  which  requires  110  to 
112  per  cent. 

When  an  analysis  is  to  be  made  the  quantity  of 
silica  is  only  known  approximately  by  experiments 
with  the  blowpipe.  With  this  uncertainty  it  is  better 
to  use  too  much  lime  than  too  little,  but  a  large  excess 
must  not  be  used,  for  most  silicates  contain  bases  some- 
what votatile,  as  potash  and  soda,  which  if  set  free  will 
cause  loss. 

The  silicate  is  ground,  passed  through  a  silk  sieve ; 
it  is  not  necessary  to  carry  this  sifting  very  far,  at  least 
if  the  silicate  is  not  very  hard  or  with  very  great  diffi- 
culty decomposed,  in  which  case  it  would  be  better  to 
pulverize  it  in  a  small  steel  crusher  than  to  employ  an 
agate  mortar. 

When  the  steel  crusher  or  mortar  is  used,  it  is 
necessary  to  digest  the  powder  obtained  in  nitric  acid, 
wash  with  water,  and  ignite  gently  to  bring  the  ma- 
terial to  its  original  purity;  when  this  is  done  the 
substance  is  placed  in  the  crucible  and  weighed,  and 
the  proper  amount  of  carbonate  of  lime  added. 

The  mixture  being  weighed,  it  should  be  mixed  as 
thoroughly  as  possible  with  a  little  strip  of  platinum. 
All  the  dust  adhering  to  the  platinum  should  be  brush- 
ed into  the  crucible  with  a  small  feather,  then  the 
feather  passed  around  the  interior  of  the  crucible  in 
such  a  manner  as  to  bring  all  together  at  the  bottom, 
and  at  the  same  time  passed  between  the  crucible  and 
the  powder,  so  as  to  detect  the  mixture. 

During  this  time  the  powder  has  absorbed  a  little 
moisture ;  the  crucible  is  placed  for  a  moment  over 
the  small  lamp*  and  heated  to  such  a  temperature  that 

*  Ordinary  gas  lamp  without  bellows.  The  lamp  with  turpen- 
tine and  bellows  is  termed  the  larger,  and  the  gas  lamp  with  only 
bellows  attached,  the  smaller. 

25 


290  SILICATES. 

each  part  of  the  surface  of  the  matter  becomes  incan- 
descent, allowed  to  cool,  again  weighed,  and  a  difference 
is  always  found,  provided  the  carbonate  contains  hygro- 
scopic water. 

The  material  being  thus  prepared,  it  is  heated  for 
fifteen  or  twenty  minutes  over  the  smaller  lamp  (gas 
lamp  fed  by  bellows)  in  such  a  manner  that  the  car- 
bonate acts  upon  the  silicate  without  fusing;  after 
having  thus  expelled  the  carbonic  acid,  the  substance 
is  placed  over  the  large  lamp,  and  it  is  necessary  that 
the  glass  produced  should  be  well  fused,  homogeneous, 
and  if  it  is  colored,  transparent;  all  the  peculiarities 
should  be  observed,  and  the  weight  thus  produced 
should  be  determined. 

The  glass  should  then  be  detached  from  the  crucible 
with  the  greatest  possible  care,  in  such  a  manner  as 
not  to  lose  any  of  it,  placed  in  an  agate  mortar,  covered 
with  sheepskin,  and  ground  with  care,  but  not  too  fine. 
The  pulverized  glass  is  then  placed  in  a  weighed  pla- 
tinum crucible,  heated  to  200°  or  800°;  and  the  glass 
to  be  analyzed  weighed. 

The  glassy  material  moistened  with  water  is  treated 
with  nitric  acid,  being  stirred  constantly  with  a  glass 
rod,  so  as  to  prevent  the  mixture  forming  a  compact 
mass  at  the  bottom  of  the  crucible.  When  all  that  is 
found  upon  the  glass  rod  is  detached,  and  it  is  heated 
over  the  lamp  to  be  sure  that  nothing  remains,  the 
crucible  is  placed  upon  the  sand-bath  and  heated  to 
such  a  temperature  that  no  more  nitric  acid  is  given 
off  and  nitrous  vapors  begin  to  form. 

If  the  material  contains  any  iron  or  manganese,  it  is 
necessary  to  wait  until  the  color  becomes  uniformly 
red  or  black,  and  then  there  should  be  added  enough 
of  a  concentrated  solution  of  nitrate  of  ammonia  to 
moisten  the  entire  mass,  which  is  heated  over  the 
sand-bath,  covering  the  crucible  with  a  funnel ;  after  a 
moment  it  is  uncovered  and  odor  observed.  If  the 


SILICATES.  291 

smell  of  ammonia  is  distinctly  perceived,  the  process  is 
continued ;  if  it  is  not,  a  drop  of  ammonia  is  added 
with  a  glass  rod,  the  mixture  stirred,  and  notice  is 
taken  if  the  smell  of  ammonia  remains  and  if  a  pre- 
cipitate is  formed;  generally  there  is  no  precipitate, 
and  it  is  then  certain  that  all  the  alumina  has  been 
precipitated  by  the  calcination.  It  is  left  to  digest  on 
the  sand-bath  until  it  is  also  certain  that  the  nitrate  of 
ammonia  has  penetrated  the  whole  mass,  then  a  little 
water  is  added,  and  the  liquid  decanted,  to  prevent 
accident,  on  a  filter. 

Water  is  again  placed  in  the  capsule,  boiled,  de- 
canted, and  washed  a  dozen  times  in  order  to  be  sure 
that  the  boiling  water  penetrated  the  entire  mass ; 
when  the  decanted  liquid  leaves  no  residue  if  evapo- 
rated on  platinum  foil,  the  washing  is  discontinued. 

The  material  submitted  to  analysis  is  then  divided 
into  two  portions — first,  the  portion  soluble  in  nitrate 
of  ammonia,  and  secondly,  the  insoluble  portion  left  in 
the  capsule. 

The  insoluble  portion  in  the  capsule  is  treated  with 
nitric  acid,  whic  his  left  to  digest  slightly  heated;  nitric 
acid  dissolves  the  alumina  and  the  peroxide  of  iron. 

If  manganese  is  not  present,  the  silica  which  remains 
is  white;  if  present,  it  is  black.  The  silica  is  washed, 
and  the  washings  evaporated  in  a  platinum  crucible 
and  ignited. 

The  mixture  of  alumina  and  oxide  of  iron  is  weighed. 

If  the  silica  contains  peroxide  of  manganese,  it  is 
washed  with  dilute  sulphuric  acid,  adding  a  crystal  of 
oxalic  acid.  The  oxalic  acid  decomposes  the  binoxide 
of  manganese  and  converts  it  into  peroxide,  which 
dissolves  in  sulphuric  acid;  the  sulphate  of  mangan- 
ese is  washed;  the  sulphate  mixed  with  sulphuric 
acid  in  a  platinum  crucible  is  heated  to  300°  to  400°, 
and  the  sulphate  of  manganese  weighed  ;  the  silica  re- 
mains in  a  state  of  purity  after  all  these  treatments 


292  SILICATES. 

and  washings,  as  much  in  the  capsule  as  upon  the  fil- 
ter, which  is  used  for  decantations.  All  these  decanta- 
tibns  should  be  made  upon  the  same  filter. 

The  filter  is  again  placed  over  the  silica  in  the  cap- 
sule, the  whole  gently  dried  upon  the  sand-bath,  then 
moderately  calcined,  when  the  silica  should  become 
white. 

The  crucible  and  its  cover  are  placed  upon  the 
balance,  and  quickly  weighed.  Inasmuch  as  the 
crucible  cools,  the  weight  that  it  is  necessary  to  place 
on  the  side  of  the  silica  to  obtain  an  equilibrium  di- 
minishes more  and  more,  by  reason  of  the  cooling  of  the 
surrounding  air;  on  the  other  hand,  as  this  cooling 
takes  place,  the  silica  absorbs  the  moisture  to  such  an 
extent  that  its  weight  is  changed  and  augmented  even 
so  as  to  be  seen. 

The  crucible  is  then  placed  again  warm  upon  the 
balance,  the  weights  taken  away  from  the  side  where 
the  silica  is,  until  the  increase  of  weight  of  the  silica 
ceases  to  be  rapid.  At  the  moment  the  balance  is  at 
rest,  the  weight  is  noted,  which  gives  the  weight  of 
the  silica. 

At  this  point  in  the  analysis  the  weight  has  been 
found;  first  of  the  silica,  secondly  of  the  mixture  of 
alumina  and  iron  containing  a  little  manganese. 

To  be  sure  that  the  silica  is  pure,  it  is  dissolved  in 
very  dilute  hydrofluoric  acid ;  if  quite  pure  it  will 
leave  no  perceptible  residue,  except  the  ash  of  the 
filter.  It  is  evaporated  with  a  little  sulphuric  acid,  and 
should  leave  no  residue. 

After  having  weighed  the  crucible  which  contains 
the  material  after  the  ignition  of  the  alumina  and 
iron,  the  mixture  is  carefully  removed  and  placed  in 
a  small  platinum  boat,  previously  weighed  in  a  small 
corked  tube;  the  boat  is  heated  to  redness,  and  again 
weighed  with  its  case  or  tube.  The  boat  is  then  intro- 
duced into  a  platinum  or  porcelain  tube,  by  aid  of  a 


SILICATES. 


293 


small  wire  which  conducts  the  boat  to  the  part  of  the 
tube,  where  it  should  be  heated.  The  tube  is  then  heated 
to  redness  and  a  current  of  hydrogen  passed  through  it.* 
When  the  iron  is  reduced,  the  stream  of  hydrogen  is 
replaced  by  a  current  of  hydrochloric  acid  gas,  which 
is  continued  for  an  hour  or  two.  Fig.  48  shows  the 
arrangement  of  this  part  of  the  analysis.  There  may 
be  placed  at  the  extremity  of  the  tube  a  small  flask,  in 
which  all  volatile  materials  will  condense  if  any  escape 
from  the  tube.  When  the  current  of  hydrochloric  acid 

*  Fig.  47  represents  a  convenient  apparatus  for  hydrogen. 
Fig.  47. 


A  and  B  are  two  bottles  of  four  or  five  litres  capacity,  and  tuhn 
lated  at  the  bottom.  By  means  of  a  rubber  tube  E  they  are  united 
in  such  away  as  to  put  them  in  communication.  The  mouth  of 
the  bottle  B  is  closed  by  a  cork,  which  is  pierced  by  a  glass  tube 
terminated  with  the  stopcock  R.  The  bottle  B  is  filled  with  frag- 
ments of  glass  to  the  level  of  the  smaller  tube,  and  a  larger  part  of 
the  space  above  with  zinc.  The  bottle  A  is  filled  with  water  and 
hydrochloric  acid.  By  opening  the  stopcock  R,  the  acidulated 
water  passes  to  the  zinc,  and  the  hydrogen  is  only  given  off  when 
the  gas  is  used. 

25* 


294 


SILICATES. 


has  passed  long  enough,  which  may  be  known  by  its 
producing  no  more  protochloride  of  iron,  it  is  stopped, 
the  hydrogen  again  passed  to  expel  the  vapor  of  hy- 
drochloric acid,  and  the  tube  left  to  cool  before  taking 
the  boat  from  it.  This  is  placed  again  in  the  case  or 
tube  and  weighed ;  the  weight  it  has  gained  gives  the 
weight  of  the  alumina. 

Fig.  48. 


The  separation  of  the  alumina  would  be  complete 
if  the  mass  was  perfectly  pure,  which  is  not  the  case, 
if  the  material  which  comes  from  the  nitrates  is  not 
sufficiently  washed. 

In  this  case,  the  material  which  has  been  treated 
with  nitric  acid,  then  with  hydrochloric  acid,  may 
contain  lime  left  with^the  alumina.  The  lime  is  found 
as  chloride  of  calcium.  The  alumina  is  moistened 
with  a  small  quantity  of  water,  which  is  decanted, 


SEPARATION   OF   THE   IRON   AND   MANGANESE.      295 

washed  several  times,  dried,  ignited  in  the  boat,  and 
weighed  in  the  glass  tube.  There  should  be  no  change 
of  weight,  and  a  drop  of  oxalate  of  ammonia  should 
give  no  precipitate  in  the  washings  if  the  alumina  was 
pure.  In  the  case  of  a  precipitate  a  diminution  of 
weight  in  the  alumina  would  be  found  at  the  same  time. 
The  alumina  is  washed,  dried,  and  weighed.  The  last 
weight  obtained  is  taken  for  the  definite  weight  of  the 
alumina,  and  the  difference  from  the  first  weight  di- 
vided by  two  gives  the  weight  of  the  lime  (CaO  =  28, 
CaCl  =  56). 

To  verify  this  weight,  all  the  lime  contained  in  the 
washings  is  precipitated  by  oxalate  of  ammonia,  ignited, 
weighed,  and  this  gives  directly  the  weight  of  the  lime. 

To  determine  by  difference  the  quantity  of  iron  and 
manganese  which  exists  in  the  material  at  the  same 
time  with  the  alumina,  we  take  from  the  entire  quan- 
tity used  for  analysis :  1st,  the  weight  of  the  pure 
alumina;  2d,  the  weight  of  the  lime;  the  difference 
gives  the  weight  of  the  mixture  of  iron  and  manga- 
nese. 

Separation  of  the  Iron  and  Manganese. 

If  the  substance  does  not  contain  manganese,  or  if 
it  is  not  necessary  to  determine  the  manganese  sepa- 
rately, the  analysis  of  the  material  insoluble  in  nitrate 
of  ammonia  is  finished.  But  if  the  iron  and  the  man- 
ganese are  to  be  separated,  recourse  may  be  had  to  the 
following  method : — 

Into  a  platinum  tube  a  current  of  vapor  of  water, 
furnished  by  a  retort  containing  distilled  water  and  a 
few  drops  of  hydrochloric  acid,  is  passed.  This  vapor 
will  be  condensed  in  the  tube,  and  will  take  with  it 
into  the  flask  or  globe  all  the  chloride  of  iron  and  man- 
ganese produced  by  the  evaporation.  This  washing 
done,  the  waters  are  placed  in  a  small  crucible,  and 
a  few  drops  of  sulphuric  acid  added,  evaporated  to 


296  ANALYSIS   OF   MATERIALS 

dryness,  and  the  sulphates  gently  calcined  until  the 
weight  is  constant;  the  mixture  of  sesquioxide  of  iron 
and  sulphate  of  manganese  is  then  weighed,  a  little 
water  poured  upon  the  sulphate,  decanted  and  washed 
upon  a  filter,  which  is  ignited  with  the  peroxide  of 
iron  and  weighed.  This  weight  is  the  oxide  of  iron, 
which,  taken  from  the  weight  previously  obtained, 
gives  that  of  the  sulphate  of  manganese.  By  adding 
the  red  oxide  of  manganese  deducted  from  the  weight 
of  the  sulphate  with  the  oxide  of  iron,  the  exact 
total  weight  of  manganese  and  iron  is  known,  which 
have  been  calculated  by  difference  at  the  time  when 
the  pure  alumina  was  weighed.  This  verification 
dispenses  with  the  direct  weight  of  the  sulphate  of 
manganese.  If,  however,  it  is  deemed  desirable  to 
determine  it,  the  sulphate  from  the  washing  should  be 
evaporated,  and  the  manganese  may  be  weighed  in 
this  form. 

The  preceding  operations  may  be  verified  in  the 
following  manner : — 

1st.  The  alumina  should  be  colored  or  slightly 
tinged  with  gray ;  it  should  be  soluble  in  bisulphate 
of  potassa  in  large  excess. 

2d.  The  oxide  of  iron,  tested  with  the  blowpipe  with 
carbonate  of  soda  in  the  oxidizing  flame,  should  give 
no  green  color. 

3d.  The  sulphate  of  manganese,  treated  with  the  sul- 
phate of  ammonia,  a  little  nitric  acid  and  ammonia, 
should  give  no  precipitate. 

Analysis  of  the  Materials  soluble  in  Nitrate  of  Ammonia. 

They  contain  1st,  lime;  2d,  magnesia,  and  sometimes 
manganese;  3d,  potassa,  4th,  soda. 

The  liquid  contains  at  first  a  certain  quantity  of 
lime,  which  has  been  introduced  to  decompose  the 
mineral.  A  quantity  of  pure  crystallized  oxalate  of 


SOLUBLE   IN   NITRATE   OF  AMMONIA.  297 

ammonia  should  be  weighed  out,  sufficient  to  precipi- 
tate more  than  the  quantity  of  lime  present.  It  suf- 
fices for  this  purpose  to  multiply  the  weight  of  the 
lime  by  2J  and  to  place  this  weight  of  pure  pulverized 
oxalate  in  the  liquid  which  is  stirred  and  left  to  settle. 
When  the  liquid  is  clear,  there  should  be  added  two 
or  three  drops  of  oxalate  of  ammonia,  and  if  there  is 
a  precipitate,  it  is  certain  there  was  lime  in  the  mate- 
rial to  be  analyzed.  There  is  added,  successively  and 
in  quantities  estimated  approximately,  solid  oxalate 
of  ammonia  and  a  few  drops  of  the  dissolved  oxalate, 
in  such  a  manner  as  to  be  sure  to  have  an  excess  of 
oxalate  of  ammonia  and  to  add  the  least  possible  quan- 
tity of  the  solution  of  the  oxalate  so  as  not  to  increase 
the  quantity  of  the  liquid.  It  is  left  to  settle  for  eight 
or  ten  hours  and  then  decanted  upon  a  filter.  All  the 
oxalate  of  lime  is  placed  on  the  filter,  by  washing  it 
little  by  little  with  warm  water.  The  precipitate  is 
then  dried,  ignited  a  sufficient  number  of  times,  and 
weighed.  This  determines  the  weight  of  the  lime. 
From  this  weight  increased  by  that  which  has  already 
been  found,  the  weight  of  the  lime  added  to  decompose 
the  mineral  is  subtracted.  This  gives  the  weight  of 
the  lime  existing  in  the  original  substance. 

The  liquid  which  remains  is  evaporated  in  a  platinum 
capsule,  until  the  fluid  is  concentrated  and  syrupy.  It 
contains  considerable  nitrate  of  ammonia,  a  little  oxa- 
late of  ammonia,  and  nitrates  of  magnesia,  manganese, 
potassa,  and  soda.  It  is  covered  with  a  glass  in  such 
a  way  as  to  transform  the  capsule  into  a  closed  vessel, 
and  the  saline  mixture  is  heated.  The  nitrate  of  am- 
monia is  converted  into  nitrous  oxide,  the  oxalate  is 
decomposed  and  volatilized,  and  there  remains  in  the 
capsule  and  on  the  glass  those  substances  which  it  is 
necessary  to  heat  to  300°  with  the  gas  or  alcohol  lamp. 
1st,  nitrates  and  subnitrates  of  magnesia  and  manga- 
nese; 2d,  nitrate  of  potassa;  3d,  nitrate  of  soda. 


298  ANALYSIS   OF   MATERIALS 

A  little  water  is  added  and  a  trace  of  pure  tartaric 
acid,  which  being  evaporated  to  dryness  is  disengaged 
with  the  vapors  of  nitric  acid.  The  interior  of  the 
capsule  will  be  filled  with  beautiful  crystals  of  vola- 
tilized oxalic  acid;  it  is  heated  to  dull  redness  by 
covering  the  capsule  in  such  a  way  that  the  carbonic 
acid  may  not  be  burned  in  the  interior.  In  this  ope- 
ration the  oxalic  acid  has  driven  off  the  nitric  acid 
and  changed  the  nitrates  into  oxalates ;  these  at  a  red 
heat  are  converted  into  carbonates,  and  if  by  chance  a 
small  quantity  of  nitrate  has  escaped  during  the  reduc- 
tion, the  carbonic  oxide  and  tartaric  acid  would  have 
eliminated  it,  so  that  there  would  remain  only  carbo- 
nates. 

Water  is  now  added  to  the  magnesia  and  manga- 
nese remaining  in  the  capsules,  and  the  alkaline  car- 
bonates are  dissolved.  It  is  decanted  upon  a  very 
small  filter,  because  it  is  not  necessary  to  wash  the 
carbonate  of  magnesia  much  ;  it  is  remarkably  soluble, 
particularly  in  cold  water,  and  therefore  the  washing 
water  should  be  boiling  hot  when  used. 

The  mixture  of  carbonate  of  magnesia  and  manga- 
nese is  heated  to  redness  and  thus  converted  into 
magnesia  and  red  oxide.  The  mixture  is  weighed  in 
the  same  capsule  in  which  the  evaporation  has  been 
made.  It  is  then  treated  with  a  boiling  concentrated 
solution  of  nitrate  of  ammonia,  and  heated  until  no 
more  ammoniacal  fumes  are  given  off.  It  is  decanted, 
and  the  insoluble  material  washed,  if  any  exists,  and 
should  be  of  a  brown  color.  The  capsule  is  then 
heated  to  redness  and  weighed.  The  difference  be- 
tween these  two  weights  gives  the  magnesia,  and 
what  remains  in  the  capsule  gives  the  weight  of  the 
manganese,  the  ammoniacal  fluid  containing  the  mag- 
nesia is  placed  aside  to  be  examined  as  directed  hereafter. 

The  soluble  carbonates  of  soda  and  potassa  are 
treated  with  hydrochloric  acid  for  experiment  in  a 


SOLUBLE   IN  NITRATE   OF  AMMONIA.  299 

glass  closed  with  a  stopper.  This  glass  is  put  in  a 
warm  place  for  ten  or  twelve  hours,  so  that  all  evolu- 
tion of  the  hydrochloric  acid  may  cease  in  the  liquid ; 
the  stopper  is  washed,  the  liquid  in  the  glass  evaporated, 
and  the  washing  waters  are  also  evaporated  in  a  plati- 
num crucible ;  the  water  and  excess  of  hydrochloric 
acid  are  driven  off,  and  a  mixture  of  chloride  of  potas- 
sium and  sodium  is  obtained,  which  always  crystallizes 
in  cubes  when  the  chloride  of  sodium  is  in  excess. 
Sometimes  these  chlorides  have  a  slight  red  color, 
caused  by  a  small  quantity  of  nitrate  left  in  the  car- 
bonates, but  any  error  is  prevented  by  heating  the 
chlorides  to  such  a  temperature  as  to  decompose  the 
chloride  of  platinum  formed.  The  chlorides  become 
black  by  the  presence  of  the  platinum,  but  this  metal 
from  the  vessels  does  not  alter  the  weight  of  the 
chlorides. 

The  alkaline  chlorides  being  weighed,  a  small  quan- 
tity of  water  is  added,  and  some  chloride  of  platinum, 
if  there  is  any  potassa.  The  mixture  of  chloride  of 
platinum  and  alkaline  salts  is  evaporated  to  a  syrupy- 
consistency,  and  treated  with  pure  alcohol.  The  resi- 
due consists  of  the  double  chloride  of  platinum  and 
potassium,  and  some  chloride  of  sodium.  It  is  dried 
and  calcined  in  order  to  reduce  the  platinum.  The 
chlorides  of  potassium  and  sodium  are  separated  by 
water;  the  mixture  is  again  ignited  and  weighed. 
The  material  which  remained  in  the  crucible  is  the 
platinum  which  proceeds  from  the  double  chloride. 
From  the  weight  obtained  we  deduct  that  of  the  chlo- 
ride of  potassium  which  it  contains;  by  subtracting 
from  the  weight  of  the  alkaline  chlorides  the  weight  of 
the  chloride  of  potassium,  the  weight  of  the  chloride  of 
sodium  is  obtained.  Having  these  weights  it  is  easy 
to  determine  that  of  the  potassa  and  soda. 

The  following  verifications  may  then  be  made :  1st. 
The  lime  which  has  been  heated  till  cessation  of  loss 


SOO  VOLATILE   MATERIALS  IN  SILICATES. 

of  weight  should  be  soluble  in  nitrate  of  ammonia, 
with  no  other  residue  but  the  ashes  of  the  filter.  2d. 
By  adding  ammonia-phosphate  of  soda  to  the  ammo- 
niacal  solution  of  magnesia,  the  bulky  precipitate  of 
phosphate  of  ammonia  and  magnesia  is  formed.  3d. 
The  manganese  is  verified  as  above  stated.  4th.  The 
chlorides  of  sodium  and  potassium  are  evaporated, 
gently  ignited,  and  when  treated  with  a  mixture  of 
alcohol  and  ether  should  not  give  any  substance  capa- 
ble of  coloring  the  flame  red,  which  would  indicate 
the  presence  of  lithia. 

The  materials  which  are  decomposed  by  acids  are 
treated  directly  in  the  same  manner  as  those  that  are 
rendered  decomposable  by  lime ;  but  it  is  necessary  to 
do  this  in  such  a  manner  that  the  silica  is  always  sepa- 
rated in  a  gelatinous  mass.  If  not,  it  is  necessary  to 
ignite  it  with  lime  to  bring  it  into  this  state.  Thus 
our  condition  is  that  the  substance  can  be  decomposed 
by  acid,  producing  gelatinous  silica.  The  glass  re- 
sulting from  the  decomposition  of  the  mineral  by  lime,  • 
should  have  for  its  weight  the  sum  of  the  weights  of 
the  materials  used,  and  the  lime  added.  The  difference 
should  be  one  milligramme,  or  two  milligrammes  at 
most ;  it  is  more  frequently  nothing. 

Examination  of  the  volatile  materials  in  silicates. 

It  has  been  seen  at  the  commencement  of  the  analy- 
sis of  the  silicates  that  it  is  necessary  to  heat  the  sub- 
stance to  a  very  high  temperature  to  expel  the  volatile 
materials.  The  water  is  freed  at  the  temperature  ob- 
tained by  the  small  lamp ;  but  when  it  is  necessary  to 
use  the  large  lamp,  the  presence  of  fluorides  is  indi- 
cated. 

The  better  way  to  make  the  presence  of  water  in  a 
mineral  evident,  is  to  place  the  material  in  a  platinum 
tube,  and  pass  a  current  of  dry  gas  through  the  tube 


VOLATILE   MATERIALS  IN   SILICATES.  301 

at  a  red  heat ;  a  tube  containing  chloride  of  calcium 
is  arranged  to  receive  the  water.  This  method  is  not 
always  adopted,  because  it  is  frequently  possible  to 
determine  other  things  with  the  water,  but  is  some- 
times useful.  In  case  there  is  only  water,  as  in  the 
zeolite,  the  ignition  and  loss  of  weight  indicate  the 
amount  of  water. 

When  there  is  any  evolution  of  volatile  materials  at 
a  high  temperature,  these  are,  as  stated,  fluorides. 
There  are  a  large  number  of  fluorides,  but  we  shall 
consider  only  those  which  may  be  expelled  by  calcina- 
tion; the  fluoride  of  silicium,  the  fluoride  of  boron, 
and  the  alkaline  fluorides. 

All  the  fluosilicates  may  be  decomposed  by  heat, 
and  all  the  fluorides,  mixed  with  a  sufficient  quantity 
of  silica,  are  changed  into  fluoride  of  silicium ;  there- 
fore the  fluoride  of  silicium  may  be  determined  at  once, 
and  it  will  be  easy  to  determine  the  other  fluorides. 

When  a  substance  contains  fluoride  of  silicium  in  a 
large  quantity,  topaz  for  example,  and  when  it  is  desir- 
able to  collect  and  determine  this  fluoride,  the  following 
method  may  be  used :  take  three  platinum  crucibles, 
a  large,  medium,  and  small  one.  In  the  small  one, 
which  has  been  weighed,  the  material  to  be  ignited  is 
placed  and  weighed ;  over  the  small  crucible,  covered 
with  its  lid,  the  medium  crucible  is  inverted  so  as  to 
form  a  cap,  and  finally  the  two  crucibles  thus  arranged 
are  placed  in  the  large  crucible ;  the  whole  are  weighed 
together  in  such  a  way  that  the  weight  of  the  appa- 
ratus, less  that  of  t]ne  topaz,  may  be  ascertained.  Then 
pour  between  the  last  two  crucibles  a  certain  quantity 
of  carbonate  of  lime  and  weigh  it.  This  gives  the 
weight  of  the  apparatus,  the  topaz,  and  the  carbonate  of 
lime. 

The  whole  is  heated  to  a  red  heat,  the  carbonate  of 
lime  is  reduced  to  quicklime,  and  it  is  heated  for  a 
long  time  over  the  large  lamp  until  the  fluoride  of 
26 


302  VOLATILE   MATERIALS  IN  SILICATES. 

silicium  is  completely  expelled.  "When  it  is  certain 
that  the  loss  of  the  topaz  is  terminated,  the  crucible  is 
taken  from  the  fire  and  weighed ;  there  should  be  no 
loss  except  of  the  carbonic  acid  of  the  lime  and  the 
water.  The  quantity  of  the  carbonate  of  lime  being 
known,  and  therefore  that  of  carbonic  acid,  it  follows 
that  the  loss  of  weight,  that  of  the  carbonic  acid  being 
deducted,  depends  entirely  upon  the  quantity  of  water 
which  may  have  passed  through  the  lime  without 
being  absorbed. 

This  done,  the  crucible  is  slightly  inclined,  the  lime 
taken  out  with  the  greatest  care,  generally  rendered 
compact  and  adhering  to  the  crucible  by  the  presence 
of  the  fluoride  of  calcium  and  the  silicate  of  lime. 
When  a  sufficient  quantity  of  lime  has  been  taken  out 
to  free  the  medium  crucible,  this  is  withdrawn,  and 
then  the  interior  crucible  is  free ;  it  is  weighed,  and 
the  loss  of  weight  gives  the  fluoride  of  silicium  which 
is  evolved. 

It  is  necessary  to  prove  that  this  is  fluoride  of  sili- 
cium. The  composition  of  fluoride  of  silicium  is  SiF3; 
if  it  .is  passed  through  the  lime,  it  forms  SiO2,CaO-h 
3CaF,  a  mixture  of  fluoride  of  calcium  and  silicate 
of  lime,  which  gives  an  excess  of  lime  again.  It  is  ne- 
cessary to  take  all  the  substance  around  the  medium 
crucible  into  the  large  crucible  and  boil  it  with  nitrate 
of  ammonia,  which  does  not  decompose  the  fluoride 
of  calcium  and  silicate  of  lime.  The  quicklime  is  thus 
disposed  of,  and  fluoride  of  calcium  and  silicate  of  lime 
remain  in  the  proportions  indicated  above  Si02CaO-f 
CaF. 

The  substance  treated  with  sulphuric  acid  should  be 
completely  converted  into  sulphate  of  lime  and  fluoride 
of  silicium.  Therefore,  after  having  treated  it  with 
nitrate  of  ammonia  and  washed  it,  sulphuric  acid  is 
added  until  no  vapors  are  given  off;  the  sulphate  of 
lime  thus  formed  is  treated  with  boiling  water  and 


VOLATILE  MATERIALS  IN  SILICATES.        308 

acid  until  wholly  dissolved.  This  washing  is  done  on 
a  filter,  so  that  the  sulphate  may  be  acted  upon  more 
readily  by  the  hot  water.  The  residue  on  the  filter  is 
ignited,  and  should  consist  of  only  a  very  small  quan- 
tity of  silica. 

Fluoride  of  silicium  and  fluorine  may  be  in  excess, 
so  that  it  may  be  possible  to  suppose  an  expulsion  of 
free  fluorine  and  fluoride  of  silicium.  But  this  is  not 
probable,  because  generally  the  silica  is  in  excess  of 
the  fluorine,  and  cannot  be  set  free  without  combining 
•with  the  silica  ;  the  topaz  containing  a  large  quantity 
of  fluorine,  and  but  little  silica,  only  sets  free  fluoride 
of  silicium.  Admitting,  however,  that  an  excess  of 
fluorine  may  exist,  it  is  at  the  same  time  supposed  that 
it  contains  no  water. 

A  sufficient  quantity  of  silica  is  added  so  that  only 
fluoride  of  silicium  will  be  set  free,  and  two  estimates 
are  made  ;  in  the  first  the  material  alone  is  determined, 
and  in  the  second  the  loss  of  the  substance  to  which 
the  silica  has  been  added.  The  difference  gives  the 
amount  of  silicium  necessary  to  neutralize  the  fluorine, 
and  the  quantity  of  free  fluorine  existing  in  the  mate- 
rials is  deducted  from  it. 


EQUIVALENT  WEIGHTS  OF  THE  ELEMENTS. 


Aluminum Al 

Antimony Sb 

Arsenic As 

Barium Ba 

Bismuth *  Bi 

Boron .     .     .  B 

Bromine :  •'%•  j     Br 

Cadmium Cd 

Caesium Ca3 

Calcium i     Ca 

Carbon C 

Cerium Ce 

Chlorine    ..........  Cl 

Chromium Cr 

Cobalt Co 

Columbium Cb 

Copper Cu 

Didymium D 

Erbium E 

Fluorine .  i     F 

Glucinum G 

Gold i     Au 

Hydrogen i     H 

Indium ^n 

Iodine I 

Iridium „  '    Ir 

Iron .  Fe 

Lanthanum  La 


H  =  l. 

13.7 
122 

75 

68.5 
208 

11 

80 

56 
133 

20 
6 

46      . 

35.5 

26.24 

29.5 

47 

31.7 

48 

56.3 

19 

9.3 
196.6 
1 

35.9 
127 

99 

28 

46.4 


EQUIVALENT   WEIGHTS   OF  THE   ELEMENTS.     30'5 


Lead               ..                          •     -    -    . 

Pb 

H=l. 

103.5' 

Li 

7 

Magnesium    •   . 

Mg 

12 

Manganese     •  .  •   . 

Mn 

27.5 

Mercury    •  .-    .- 

Hg 

100 

Molybdenum      -  .-    .- 

Mo 

48 

Nickel       ..-...• 

Ni 

Nitrogen                  .                 ..... 

N 

14 

Osmium 

Os 

996 

O 

8 

Palladium      

Pd 

53.3 

Phosphorus   -             . 

P 

31 

Platinum        -    .         . 

Pt 

98.7 

Potassium      .     .     .     .     .     .  .    „    .     . 

K 

39.1 

Ehodium  .     .     . 

Eh 

52.2 

Eubidium      .......... 

Eb 

85.4 

Euthenium    

Eu 

52.2 

Selenium  

Se 

39.7- 

Silicium    ...     ... 

Si 

14 

Silver  ...;... 

AD- 

108 

Sodium     

Na 

23 

Strontium      

Sr 

43.75* 

Sulphur    

S 

16 

Tantalum  ;»   .  .    .     .     .     .     .     .     . 

Ta 

91 

Tellurium  M        ... 

Te 

64 

Thallium  -* 

Tl 

204 

Thorium,  

Th 

115.7- 

Tin    ,   

Sn 

59 

Titaaium  

Ti 

25 

Tungsten  

W 

92 

Uranium  

u 

60; 

y 

51  3 

Yttrium    

Y 

309 

Zinc      

Zn 

326 

Zirconium 

Zr 

44.8- 

26* 


EQUIVALENT  WEIGHTS  OF  COMPOUND  BODIES. 


H 


(  KO,  S03,  A1203,  1 

474.6 

\    3S03-f24HO    j 

Alumina     .         .        ,,         .         . 

A1203 

78.8 

Ammonia   .         .         .... 

NH3 

17 

carbonate  of         .         ._ 

2NH40,  3C02 

118 

Ammonium         .         .         .         . 

NH4 

18 

NH  Cl 

53.5 

NH  0 

26 

NH4Cl,4PtCl 

223.2 

Antimonious  acid 

BbO. 

153' 

Arsenate  of  magnesia-ammonia  . 

2MgO,NH40,As05+HO 

190 

Arsenic  acid        .... 

As05 

115 

Arsenious  acid    .... 

As03 

99 

Barium,  chloride  of     . 

BaCl 

104 

silicofluoride  of     . 

3BaF,  2SiF3 

419.1 

Baryta         ..... 

BaO 

76.5 

carbonate  of    . 

BaO,  C02 

98.6 

/•]  i  miYi  •")  t  P   ^^ 

BaO,  CrO 

1070 

j.zi  /  .0 

Berylla  (glucina)        .       '  .   '     . 
Biborate  of  soda          ;      '  .   '     •'. 

Be'203    3 
NaO,  2B03-hlOHO 

52.2 
190.8 

Binoxalate  of  potassa       .  .   .     , 

KO,  2C20,+3UO 

146.2 

Bismuth,  teroxide  of  .      __  .         . 

Bi03 

232 

Bitartrate  of  potassa  .         .         • 

KO,  HO  T 

188.2 

Cadmium,  oxide  of     .         .   *    '•  ' 

CdO 

64 

Calcium,  chloride  of  . 

CaCl 

55.5 

Carbonic  acid     .... 

CO2 

22 

Chromate  of  lead 

PbO,  Cr03 

162.4 

Chromic  acid      .... 

Cr03 

50.7 

Chromium,  sesquioxide  of  . 

Cr203 

77.4 

Cobalt,  protoxide  of   .      ,  ,  -,_,    . 

CoO 

37.5 

Copper,  protoxide  of  .         .         , 

CuO 

39.7 

—  i  suboxide  of    .      *  .'  *     ^ 

Cu,0 

71.4 

Cyanide  of  silver  '      ;      •  .  •      i 

AgCy 

134 

26 

Ferrocyanide  of  potassium           » 

2KCy,  FeCy=KaCfy 

184.4 

EQUIVALENT  WEIGHTS   OF   COMPOUND   BODIES.      307 


Ferrocyanide   of  potassium  con- 
taining water  of  crystallization 
Fluoride  of  calcium 
Hydrochloric  acid 
Iodide  of  palladium 
of  potassium 
Iron,  protoxide  of 
sesquioxide  of 
Lead,  acetate  of 
chloride  of 

/  2KCy,  FeCy-f-3HO  ) 
\     =K2Cfy+3HO      } 
CaF 
HC1 
Pdl 
KI 
FeO 
Fe208 

PbO,  A-|-3HO 
PbCl 

PKO 

H=-l. 

211.4 

39 
36.5 
180.4 
166.3 
36 
80 
189.5 
139.2 

m»7 

red  oxide  of               »         . 
Lime          _.,      :  .                 '  .  ,   -  ., 
carbonate  of                 .  :    •  . 
Magnesia    .         ,  ;                .         . 
Manganese,  peroxide  of 

PbO,  Pb203 
CaO 
CaO,  C02 
MgO 
MnO, 

MnO    Mil  f> 

•  t 

342.5 

28 
50 
20 
43.6 

mo 

MiiO 

OK   a 

Mercury,  protochloride  of  . 
protoxide  of          .         . 
subchloride  of 
suboxide  of 
Molybdenum,  biuoxide  of    . 
Molybdic  acid     .... 
Nickel,  protoxide  of    . 
Nitrate  of  baryta 
of  lead    .... 

HgCl 
HgO 

Hg2cr 

Hg20 
Mo02 
Mo03 
NiO 
BaO,  N05 
PbO,  N05 

"KTl    "NTO 

135.5 
108 
285.5 
208 
62 
70 
37.6 
130.5 
165.7 

A  rrC\     NT> 

i  ^n  i 

of  soda  .... 
of  strontia 
Nitric  acid           .... 

NaO,  N05 
SrO,  N06 
N05 

rirv   ivrrj 

1  /U.I 

85 
105.8 
54 

/«o 

Oxalic  acid          .         .       '.     .  * 

C203 

qtrr)    p  f\ 

36 

/>q 

aPhosphate  of  magnesia 

2MgO,  P05 

OMnf)     pf) 

111 
1  qq 

crystallization 
Phosphoric  acid 

2NaO,HO,POs+24HO 

P05 
KO 

358 
71 

47  2 

••             bichromate  of 

KO,  2Cr03 
TTO  r*n 

148.6 

/•Q    0 

—  —  —  chlorate  of      •         .         . 
chromate  of    . 
hydrate  of      .         .    ;.:'* 
Potassium,  chloride  of        .        . 

KO,  C106 
KO,  Cr03 
KO,  HO 
KC1 

122.7 
97.9 
56.2 

74.7 

80S      EQUIVALENT  WEIGHTS  OF   COMPOUND  BODIES. 


Potassium,  platino-chloride  of    . 
Silicic  acid  .. 

Silicium,  terfluoride  of 
Silver,  chloride  of 

oxide  of  . 

Soda 

carbonate  of        ... 

carbonate     of,     containing 

water  of  crystallization,    . 

hydrate  of . 

Sodium,  chloride  of    . 

Stannic  acid 

Strontia      ....... 

Sulphate  of  ammonia 

of  baryta     .         ..        ^ 

of  copper    . 

of  lead 

of  lime         ..        .,        » 

of  potassa    .. 

of  protoxide  of  iron.     . 

of  soda         .         .         . 

of  strontia  . 

Sulphide  of  antimony 

of  arseniq.    . 

of  copper,     . 

of  lead 

of  mercury 

of  molybdenum.  . 

of  silver      .    '   '.' 

--  of  zinc         * 

Sulphuretted:  hydrogen       /'       • 
Sulphuric  aeid,  .         .         .'       « 

— — r-  Ohydrated) 

Sulphurous^  acid          .        '. 
Tin,  protoxide  of         * 
Titanic  acid,        ." 
Tungstic.  afiid,    . 
Water         .         .         .         ." 
Zinc,,Qxide  of     . 


KC1,  PtCl2 

SiO, 

SiF, 

AgCl 

AgO 

NaO 
NaO,CQ2 

NaO,  COo-flOHO, 

NaO,  HO 

NaCl. 

Su02 

SrO/ 

NH40,  S034-H0 

BaO,  S03 

CuO,S03-h5HO. 

PbO,  S03 

CaO,  S03 

KO,  S03 

FeO,  S034-7HO 

'  NaO,  SO 

SrO,  S03 

SbS3 

AsS3 

CuS 

PbS 

HgS 

MoS2 

AgS, 

ZnS 

HS 

S03 

BP,  S0ff 

SnO' 
Ti02 
W08 
HO 
ZuO  , 


ERR  ATU,M.t 
Page  287,  4th  line  from  top  for  Fig.  43  r^/Big.  45. 


INDEX. 


Acid,  arsenic,  224 

arsenious,  224 

boracic,  221 

carbonic,  217,  227 

columbic,  176 

hydrocyanic,  255 

molybdic,  181,  185 

nitric,  221,  225 

phosphoric,  223,  226 

phosphorous,  detection,  285 

silicic,  221,  226,  227 

sulphuric,  222,  226 

tantalic,  177 

tartaric,  80,  81 

titanic,  171,  172,  173,  176 

tungstic,  178 

vanadic,  185,  187 
Alkalies,  16,  227 

and  magnesia,  25 
Alkalimetry,  240 
Alkaline  earths,  31 
Alum,  33 

iron-ammonia,  34 
Alumina,  33,  228 

and  baryta,  33 

and  chromium  sesquioxide,  35 

and  fluorine,  153 

and  glucina,  151 

and  iron  sesquioxide,  38 

and  magnesia,  37 

and  phosphoric  acid,  37 

and  potash,  148 

chrome-alum,  34 

phosphates  of,  36 
Aluminum  with  iron,  203 
Amalgams,  70 
Ammonia,  225 

and  magnesia  phosphate,  23 


Ammonia — 

and  soda  phosphate,  22 

estimation,  18,  23 

nitrate  of,  296 

and  soda  sulphate,  18 
Amphibole,  150 
Analysis  of  nitre,  252 

volumetric,  50,  52 
Antimony,  224 

and  arsenic,  88 

and  tin,  90 

and  potassa  tartrate,  80 

and  copper,  82 

and  iron,  84 

and  lead,  80,  83 

and  silver,  84 

and  tin,  87 

chloride,  95 

estimation,  80 

sulphide,  81 
Apatite,  29 

Aqua    amygdalarum   amararum, 
255 

laurocerasi,  255 
Argentan,  97 
Arsenic,  95,  227 

and  antimony,  88 

and  arsenious  acid,  224 

and  cobalt,  104 

and  iron,  202 

and  lead,  77 

and  nickel,  98 

and  tin,  78 

antimony,  and  tin,  90 

chloride,  95 

poisoning  by,  258 

sulphide,  91 

with  iron,  202 


310 


INDEX. 


Ashes  of  plants,  228 

of  seeds,  229 

Ash  of  refining  hearth,  205 
Assay  of  iron,  50,  52 

silver,  67 

Barite,  31 

Baryta  and  alumina,  33 

and  strontia  separation,  33 

estimation,  31 
Bell  metal,  72 
Berthierite,  84 
Beryl,  151 
Bismuth  and  copper,  76 

lead  and  tin,  74 
Bitter  spar,  27 
Black  cobalt  ore,  107 
Bleaching  powder,  2;5Q 
Blende,  55 

pitch,  195 

Blondlot,    plan    to  detect    phos- 
phorus, 282 
Blue  vitriol,  53 
Bog  iron-ore,  49. 
Bone-ash,  27 
Boracic  acid,  14£,  221 
Bournonite,  82 
Brass,  58 

Bromide  of  sodium,  212 
Bromine,  222 
Bronze,  72 
Brown  iron  ore,  185 

Cadmium  and  copper,  60        .  > 

and  zinc,  60 
Calcium  with  iron,  203 
Carbon  estimation,  200 
Carbonate  of  lead,  62. 

of  potassa  and  magnesia,  21 

of  soda,  223 

of  ainc,  57 

Carbonates  in  water,  220 
Carbonic  acid  estimation,  21,  27, 

217,  227 
Cast-iron,  200 
Celestite,  31 
Cements,  211 
Cerite,  158 


Cerium  oxide,  160 

Chalcopyrite,  53 

Chloride  of  lime  valuation,  2501 

of  lithium,  170 

of  silver,  14 

of  sodium,  13,  212,  214, 

of  tantalum,  178 

of  thorium,  168 

of  zirconium,  157 
Chlorides  of  mercury,  antimony, 
and  arsenic,  95 

of    potassium,    sodium,    and 

magnesium,  25 
Chlorimetry,  250 
Chlorine,  222,  226 

and  bromine,  222 

estimation,  14 
Chrome-alum,  34 

iron-ore,  187 

yellow,  189 

Chromic  acid  and  lead,  189 
Chromite,  187 
Chromium  estimatiop,  65. 

with  iron,  204 
Chrysolite,  144 
Cinnabar,  72 
Clausthalite,  198 
Clay,  210 
Cobalt  and  arsenic,  104 

and  manganese,  1,07 

and  iron,  106 

ores,  black,  107 

speiss,  104 

with  iron,  204 
Cobaltite,  104 
Coins,  gold  and  copper,  68 
Coin,  silver,  66 
Columbic  acid,  176 
Columbite,  176 
Common  limestone,  211 

salt,  214 
Compounds,    equivalent    weights. 

of,  306 
Copper,  203,  224,  227 

amalgam,  70 

and  antimony,  82 

and  arsenic,  76 

and  bismuth,  76, 


INDEX. 


311 


Copper — 

and  cadmium,  60 

and  gold,  68 

and  iron,  54 

and  lead,  82 

and  tin,  72 

and  silver,  66 

and  zinc,  69 

estimation,  53 

nickel,  and  zinc,  97 

sulphate,  63 

sulphide,  53,  82 

with  iron,  203 
Cryolite,  155 

Datolite,  145 

Detection  of  unoxidized  phospho- 
rus, 278 

Didymium  oxide,  160 

Dolomite,  27 

Dussard,  plan  to  detect  phospho- 
rus, 282 

Earthy  ore  of  cobalt,  107 
Elements,  equivalent  weights  of, 

304 

Epidote,  150 
Epsom  salt,  21 
Erbia,  167 
Equivalent  weights  of  elements, 

304 
weights  of  compound  bodies, 

306 

Examination  of  volatile  matters 
in  silicates,  300 

Feldspar,  147 

Ferrocyanide  of  potassium,  257 

Fluorine,  153,  224 

and  alumina,  153 

and  lime,  154 

and  sodium,  155 

estimation,  30 
Fluorite,  154 

Gadolinite,  164 
Galenite,  61 
Garnet,  150 


German  silver,  97 
Glass,  209 
Glauber's-salt,  21 
Glaucina  and  alumina,  151 
Glucina,  151 

preparation,  162 
Gold  and  copper,  68 

and  silver,  69 

coins,  68 
Graminacese,  232 
Green,  schweinfurt,  76 
Guano,  232 
Gun-metal,  72 
Gunpowder,  254 
Gypsum,  81 

Hematite,  42 
Hydraulic  limestone,  211 
Hydrocyanic  acid,  255 
Hydrogen  purification,  42 
sulphuretted,  219 

Idocrase,  150 

Ilvaite,  143 

Incrustations  from  salt-pans,  215 

Indium,  133 

combinations  of,  136 

preparation  of,  136 

properties  of,  136 

purification  of,  135 

separation  of,  1 34 
Iodide  of  sodium,  212 
Iodine,  222 
Iridium,  112,  133 

combinations,  137 

preparation,  136 

separation,  134 
Iridosmine,  118 
Iron-ammonia-alum,  34 

and  antimony,  84 

and  cobalt,  106 

and  copper,  54 

and  magnesia,  144 

and  manganese,  47 

and  titanium,  172,  174 

assay,  50,  52 

cast,  200 

estimation,  49 


812 


INDEX. 


Iron — 

meteoric,  109 

nickel  and  cobalt,  110 

ore,  bog,  49 

brown,  185 

chrome,  187 
sesquioxide  and  alumina,  38 

and  phosphoric  acid,  41 

and  protoxide,  44 
titanic,  172 

zinc  and  manganese,  oxides, 
59 

Lanthanum  oxide,  160 
Lead  and  antimony,  80,  83 

and  arsenic,  77 

and  chromic  acid,  189 

and  copper,  82 

and  silver,  65 

and  tin,  73 

and  vanadic  acid,  188 

bismuth,  and  tin,  74 

carbonate  of,  62 

estimation,  62 

molybdate  of,  181 

phosphate  of,  83 

selenide  of,  198 

vanadate,  187 

white,  62 
Lime,  223 

and  fluorine,  154 

chloride  of,  250 

estimation,  27,  31 

oxalate  and  phosphate  of,  238 

sulphate  of,  31 
Limestone,  211 
Limonite,  42 
Lithia,  169 
Lithium,  chloride,  170 

Magnesia,  223 

and  alkalies,  25 

and  alumina,  37 

and  ammonia  phosphate,  23 

and  iron,  144 

and  lime,  27 

and  lithia,  169 

and  manganese,  46 


Magnesia — 

and  phosphate  of  ammonia, 
23 

and  potassa,  sulphate,  19 

and  sesquioxide  of  iron,  46 

estimation,  19,  25,  28 

carbonate  of  potassa  and,  21 

sulphate  of,  21 

of  potassa  and,  19 
Magnesium,  chloride  of,  25 

with  iron,  203 
Magnetite,  44 
Manganese  and  iron,  47,  179,  203 

and  lime,  46 

and  magnesia,  46 

and  zinc,  59 

cobalt  or  nickel,  107 

ore,  valuation  of,  248 

with  iron,  203 
Marl,  211 

Marsh's  test  for  arsenic,  272 
Materials   soluble  in    nitrate   of 

ammonia,  296 
Menaccanite,  172 
Mercury,  70 

and  copper,  70 

chloride,  95 

oxide  of,  with  oxide  of  lead, 
72 

protoxide,  72 
Meteoric  iron,  109 
Microcosmic  salt,  22 
Mineral  waters,  216 
Minium,  72 

Mitscherlich's  plan  to  detect  phos- 
phorus, 278 
Molybdate  of  lead,  181 
Molybdenite,  184 
Molybdenum  with  iron,  204 
Molybdic  acid,  183,  208 

Natrolite,  141 

Neubauer  and  Fresenius,  plan  to 

detect  phosphorus,  282 
Niccolite,  98 
Nickel,  and  arsenic,  98 

and  cobalt,  99 

and  copper,  97 


INDEX. 


313 


Nickel— 

and  iron,  204 

and  zinc,  97 

cobalt  and  iron,  99 

pure  preparation,  98 

speiss,  98 

with  iron,  204 
Niobite,  176 
Nitrate  of  ammonia,  296 
Nitre,  analysis  of,  252 
Nitric  acid,  221,  225 

Olivine,  144 

Ores,  black  cobalt,  107 

brown  iron,  185 

chrome  iron,  187 

manganese,  248 

platinum,  111,  114 

red  silver,  84 

tellurium,  138 
Organic  matters  in  soil,  225 
Orthoclase,  147 
Osmium,  113 
Oxalate  and  phosphate  of  lime, 

238 
Oxide  of  cerium,  159,  160 

of  didymium,  160 

of  lanthanum,  160 
Oxides  of  manganese,  iron,   and 
zinc,  59 

of  thallium,  129 
Oxygen  estimation,  42,  53 

Palladium,  111 

Permanganate  of  potash  prepara- 
tion, 50 
Pewter,  73 

Phosphate  and  oxalate  of  lime,  238 
of  alumina,  36 

of  magnesia  and  ammonia,  23 
of  soda  and  ammonia,  22 
Phosphoric  acid,  223,  226 
and  alumina,  37 
and  arsenic  acid,  63 
and  magnesia,  24 
and  oxide  of  lead,  63 
and  sesquioxide  of  iron, 
41 

27 


Phosphoric  acid — 

estimation,  23 
separation  from    bases, 

29 

Phosphorous  acid,  detection,  285 
Phosphorus,  poisoning  by,  288 

with  iron,  202 
Pitch-blende,  195 
Plant  ashes,  228 
Platinum  metals  and  ore,  111,  114 

residues,  121 
Poisoning  with  arsenic,  258 

poisoning  with   phosphorus, 

278 

Potash  and  alumina,  148 
Potashes,  247 
Potash  permanganate,  50 
Potassa,  222,  226 

and  antimony,  tartrate,  80 

and  magnesia,  carbonate,  21 
sulphate,  19 

and  soda,  tartrate,  16 
Potassium,  chloride  of,  25 

ferrocyanide,  257 
Powders,  bleaching,  250 
Proustite,  86 
Pyrargyrite,  84 
Pyromorphite,  63 
Pyroxene,  150 

Red  silver-ore,  84 
Rhodium,  112 
Rochelle-salt,  16 
Ruthenium,  113 
Rutile,  175 

Saline  springs,  216 
Salt  pans,  incrustations  from,  215 
Scheelite,  181 

Scherer's  plan  to  detect  phospho- 
rus, 278 

Schreibersite,  109 
Schweinfurt  green,  76 
Selenium  and  selenides,  195,  198 

soot,  197 
Seeds,  ashes  of,  229 
Seignette  salt,  1 6 
Selenide  of  lead,  198 


314 


INDEX. 


Siderite,  46 

Silicates,  150,  209,  285 

volatile  matters  in,  300 
Silicic  acid,  142,  221,  226,  227 
Silicon  with  iron,  201 
Silver  and  antimony,  84 

and  arsenic,  84 

and  copper,  66 

and  gold,  69 

and  lead,  65 

and  mercury,  71 

assay,  67 

chloride,  14 

coin,  66 

ore,  red,  84 

pure  preparation,  67 
Slags,  205 
Smithsonite,  57 
Smaltite,  103 
Soda,  222,  226,  247 

and  ammonia,  18 

carbonate  of,  223 

phosphate,  22 
sulphate,  18 

and  lime,  147 

and  potassa  estimation,  16 
tartrate,  16 

estimation,  14 

sulphate,  15 
Sodium,  chloride,  13 

iodide,  bromide,  and  chloride, 
212 

potassium,    and   magnesium 

chlorides,  25 
Sodium  and  fluorine,  155 
Soft  solder,  73 
Soils,  224 
Solder,  73 
Soot,  selenium,  197 
Spathic  iron,  46 
Specular  iron  ore,  42 
Speiss  cobalt,  103 

nickel,  98 
Sphalerite,  55 
Sphene,  171 
Spinel,  37 
Springs,  saline,  216 
Strontia,  223 


Strontia — 

and  baryta  estimation,  33 

and  lime,  31 

estimation,  31 
Sulphate  of  baryta,  31 

of  copper,  53 

of  lime,  31 

of  potassa  and  magnesia,  19 

of  soda,  15 

and  ammonia,  18 

of  Strontia,  31 

of  thoria,  168 
Sulphide  of  antimony,  81 

of  arsenic,  91 

of  copper,  53,  82  . 

of  lead,  61 

of  zinc,  55 
Sulphur  and  iron,  204 

estimation,  63,  81,  83,  95 
Sulphuretted  hydrogen,  219 
Sulphuric  acid,  222,  226,  227 

Tantalic  acid,  176,  177 
Tantalite,  177 
Tantalium  chloride,  178 
Tartar  emetic,  80 
Tartaric  acid  estimation,  80,  81 
Tartrate  of  antimony  and  potassa, 
80 

of  soda  and  potassa,  16 
Tellurium  and  bismuth,  140 

ore,  138 

Tetradymite,  140 
Tetrahedrite,  91 
Thallium,  126 

detection,  129 

estimation,  130 

estimation  volumetric,  132 
Thomsonite,  141 
Thoria,  sulphate,  168 
Thorite  and  thoria,  167 
Thorium,  chloride,  168 
Tin,  73 

amalgam  of,  71 

and  antimony,  87 

and  arsenic,  78 

and  copper,  72 

and  lead,  73 


INDEX. 


315 


Tin— 

arsenic,  and  antimony,  90 
bismuth,  and  lead,  74 

Titanic  acid,  171,  172,  173 
iron,  172 

Titanite,  171 

Titanium  and  iron,  172,  174 

Topaz,  153 

Triphylite,  168 

Tungstic  acid,  179,  181 
and  lime,  181 

Type  metal,  80 

Ulexite,  146 
Uraninite,  192 
Uranium  oxide,  192 

Vanadate  of  lead,  187 
Vanadic  acid,  185,  187 
Vanadinite,  187 
Valuation  of  manganese  ores,  248 

of  soda,  247 
Vanadium,  185 

with  iron,  204 
Vegetable  ashes,  231 
Vitriol,  blue,  53 

Volatile  matters  in  silicates,  300 
Volumetric  analysis,  50,  52 

Water  estimation,  15,  216,  225 
Wavellite,  36 


Weights   of   compounds,   equiva- 
lent, 306 

of  elements,  equivalent,  304 
Well  waters,  216 
Wet  assay  of  iron,  50 
White  lead,  62 

Widmannstatten'a  figures,  109 
Wolframite,  178 
Wood  ashes,  231 
Wulfenite,  181 

Yellow  chrome,  189 
Yttria,  165 

and  erbia  separation, '166 

Zinc  blende,  55 

and  cadmium,  60  '    . 

and  copper,  59   • 

and  iron,  64 

and  nickel,  97 

carbonate,  57 

iron  and  manganese,  59 

sulphates  of  iron,  copper,  and, 
58 

sulphide,  55 
Zinkenite,  83 
Zircon,  156 
Zirconia,  156 

and  iron,  157 

and  silver,  157 
Zirconium  chloride,  157 


THE    END. 


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By  OLIVER  BYRNE.  Illustrated  by  Numerous  Wood  Engrav- 
ings, 12mo. $3  63 

•DYENE.— THE  PEACTICAL  METAL-WOEKEE'S  ASSISTANT: 
Comprising  Metallurgic  Chemistry ;  the  Arts  of  Working  all 
Metals  and  Alloys;  Forging  of  Iron  and  Steel;  Hardening  and 
Tempering ;  Melting  and  Mixing ;  Casting  and  Founding ; 
Works  in  Sheet  Metal ;  the  Processes  Dependent  on  the 
Ductility  of  the  Metals ;  Soldering ;  and  the  most  Improved 
Processes  and  Tools  employed  by  Metal-Workers.  With  the 
Application  of  the  Art  of  Electro-Metallurgy  to  Manufactu- 
ring Processes ;  collected  from  Original  Sources,  and  from  the 
Works  of  Holtzapffel,  Bergeron,  Leupold,  Plumier,  Napier,  and 
others.  By  OLIVER  BYRNE.  A  New,  Revised,  and  improved 
Edition,  with  Additions  by  John  Scoffern,  M.  B  ,  William  Clay, 
Wm.  Fairbairn,  F.  R.  S.,  and  James  Napier.  With  Five  Hun- 
dred and  Ninety-two  Engravings ;  Illustrating  every  Branch 
of  the  Subject  In  one  volume,  Svo.  652  pages  .  $7  00 

•nYENE.— THE  PEACTICAL  MODEL  CALCITLATOE: 

For  the  Engineer,  Mechanic,  Manufacturer  of  Engine  Work, 
Naval  Architect,  Miner,  and  Millwright.  By  OLIVER  BYRNE. 
1  volume,  8vo.,  nearly  600  pages  .  .  .  .  $4  50 

•DEMEOSE.— MANUAL  OF  WOOD  CAEVING :  With  Practical  II- 
lusttations  for  Learners  of  the  Art,  and  Original  and  Selected  de- 
signs. By  WILLIAM  BEMROSE,  Jr.  With  an  Introduction  by 
LLEWELLYN  JEWITT,  F.  S.  A.,  etc.  With  128  Illustrations.  4to., 
cloth $3  00 


HENRY  CAREY  BAIRD'S  CATALOGUE. 


TDAIRD.— PROTECTION  OF  HOME  LABOR   AND  HOME    PRO- 
B    DUCTIONS   NECESSARY   TO   THE   PROSPERITY    OF    THE 

AMERICAN  FARMER : 

By  HENRY  CAREY  BAIRD.     8vo.,  paper      .  10 

•DAIRD.— STANDARD  WAGES  COMPUTING  TABLES: 

An  Improvement  in  all  former  Methods  of  Computation,  so  ar- 
ranged that  wages  for  days,  hours,  or  fractions  of  hours,  at  a  spe- 
cified rate  per  day  or  hour,  may  be  ascertained  at  a  glance.  By 
T.  SPANGLER  BAIRD.  Oblong  folio $5  00 


B 


B 


ISHOP.— A  HISTORY  OF  AMERICAN  MANUFACTURES: 

From  1608  to  1866  :  exhibiting  the  Origin  and  Growth  of  the  Prin- 
cipal Mechanic  Arts  and  Manufactures,  from  the  Earliest  Colonial 
Period  to  the  Present  Time  ;  with  a  Notice  of  the  Important  In- 
ventions, Tariffs,  and  the  Results  of  each  Decennial  Census.  By 
J.  LEAXDER  BISHOP,  M.  D. ;  to  which  are  added  Notes  on  the 
Principal  Manufacturing  Centres  and  Remarkable  Manufactories. 
By  EDWARD  YOUNG  and  EDWIN  T.  FREEDLEY.  In  three  vols. 
8vo $10  00 

OX.— A  PRACTICAL  TREATISE  ON  HEAT  AS  APPLIED  TO 
THE  USEFUL  ARTS : 

For  the  use  of  Engineers,  Architects,  etc.  By  THOMAS  Box,  au- 
thor of  "Practical  Hydraulics."  Illustrated  by  14  plates,  con- 
taining 114  figures.  12mo $4  25 

HABINET  MAKER'S  ALBUM  OF  FURNITURE  : 

Comprising  a  Collection  of  Designs  for  the  Newest  and  Most 
Elegant  Styles  of  Furniture.  Illustrated  by  Forty-eight  Large 
and  Beautifully  Engraved  Plates.  In  one  volume,  cblong 

$5  00 

APMAN.— A  TREATISE  ON  ROPE-MAKING : 
As  practised  in  private  and  public  Rope-yards,  with  a  Description 
of  the  Manufacture,  Rules,  Tables  of  Weights,  etc.,  adapted  to  the 
Trade ;  Shipping,  Mining,  Railways,  Builders,  etc.     By  ROBERT 
CHAPMAN.     24mo •>»'...       •     $150 

pALVERT.— LECTURES  ON  COAL-TAR  COLORS  AND  ON  RE- 
U    CENT  IMPROVEMENTS  AND  PROGRESS  IN  DYEING  AND 
CALICO  PRINTING. 

Embodying  Copious  Notes  taken  at  the  last  London  International 
Exhibition,  and  Illustrated  with  Numerous  Patterns  of  Aniline 
and  other  Colors.  By  F.  GRACE  CALVERT,  F.  R.  S.,  F.  C.  S.  8vo., 
cloth  $1  50 


CH 


HENRY  CAREY  BAIRD'S  CATALOGUE.  .  7 

pRAIK.— THE   PRACTICAL   AMERICAN    MILLWRIGHT   AND 
^     MILLER. 

Comprising  the  Elementary  Principles  of  Mechanics,  Me- 
chanism, and  Motive  Power,  Hydraulics  and  Hydraulic 
Motors,  Mill-dams,  Saw  Mills,  Grist  Mills,  the  Oat  Meal  Mill, 
the  Barley  Mill,  Wool  Carding,  and  Cloth  Fulling  and  Dress- 
ing, Wind  Mills,  Steam  Power,  &c.  By  DAVID  CRAIK,  Mill- 
wright. Illustrated  by  numerous  wood  engravings,  and  five 
folding  plates.  1  vol.  Svo.  .  .  .  .  $5  00 

PAMPIN.— A  PRACTICAL  TREATISE  ON  MECHANICAL  EN- 

U     GINEERINGt 

Comprising  Metallurgy,  Moulding,  Casting,  Forging,  Tools, 
Workshop  Machinery,  Mechanical  Manipulation,  Manufacture 
of  Steam-engines,  etc.  etc.  With  an  Appendix  on  the  Ana- 
lysis of  Iron  and  Iron  Ores.  By  FRANCIS  CAMPIN,  C.  E.  Tc 
which  are  added,  Observations  on  the  Construction  of  Steam 
Boilers,  and  Remarks  upon  Furnaces  used  for  Smoke  Preven- 
tion ;  with  a  Chapter  on  Explosions.  By  R.  Armstrong,  C.  E., 
and  John  Bourne.  Rules  for  Calculating  the  Change  Wheels 
for  Screws  on  a  Turning  Lathe,  and  for  a  Wheel-cutting 
Machine.  By  J.  LA  NICCA.  Management  of  Steel,  including 
Forging,  Hardening,  Tempering,  Annealing,  Shrinking,  and. 
Expansion.  And  the  Case-hardening  of  Iron.  By  G.  EDE. 
Svo.  Illustrated  with  29  plates  and  100  wood  engravings. 

$6  00 

pA.MPIN.— THE    PRACTICE    OF  HAND-TURNING  IN  WOOD, 

^     IVORY,  SHELL,  ETC. : 

With  Instructions  for  Turning  such  works  in  Metal  as  may  be 
required  in  the  Practice  of  Turning  Wood,  Ivory,  etc.  Also 
an  Appendix  on  Ornamental  Turning.  By  FRANCIS  CAMPIN  , 
with  Numerous  Illustrations,  12mo.,  cloth  .  .  $3  00 

p&PRON  DE  DOLE.— DUSSATTCE.— BLUES  AND  CARMINES  OF 

U     INDIGO, 

A  Practical  Treatise  on  the  Fabrication  of  every  Commercial 
Product  derived  from  Indigo.  By  FELICIEN  CAPRON  DE  DOLE 
Translated,  with  important  additions,  by  Professor  H.  Dus- 
SAUCE.  12mo.  .  $2  50 


8  HENRY  CAREY  BAIRD'S  CATALOGUE. 

pAREY.— THE  WORKS  OF  HENRY  C.  CAREY : 

CONTRACTION  OR  EXPANSION?  REPUDIATION  OR  RE- 
SUMPTION ?  Letters  to  Hon.  Hugh  McCulloch.  8vo.  38 

FINANCIAL  CRISES,  their  Causes  and  Effects.    8vo.  paper 

25 

HARMONY  OF   INTERESTS;    Agricultural,   Manufacturing, 

and  Commercial.     8vo.,  paper $1  00 

Do.  do.  cloth          .        .         .     $1  50 

LETTERS  TO  THE  PRESIDENT  OF  THE  UNITED  STATES. 
Paper .  .  .  $1  00 

MANUAL  OF  SOCIAL  SCIENCE.  Condensed  from  Carey's 
"Principles  of  Social  Science."  By  KATE  McKEAN.  1  vol. 
12mo .  $2  25 

MISCELLANEOUS  WORKS:  comprising  "Harmony  of  Inter- 
ests," "Money,"  "Letters  to  the  President,"  "French  and 
American  Tariffs,"  "Financial  Crises,"  "The  Way  to  Outdo 
England  without  Fighting  Her,"  "Resources  of  the  Union," 
"The  Public  Debt,"  "Contraction  or  Expansion,"  "Review 
of  the  Decade  1857 — '67,"  "  Reconstruction,"  etc.  etc.  1  vol. 
8vo.,  cloth $4  50 

MONEY:  A  LECTURE  before  the  N.  Y.  Geographical  and  Sta- 
tistical Society.  8vo.,  paper 25 

PAST,  PRESENT,  AND  FUTURE.     8vo.  .        .        .     $2  50 

PRINCIPLES  OF  SOCIAL  SCIENCE.     3  volumes  8vo.,  cloth 

$10  00 

REVIEW  OF  THE  DECADE  1857— '67.     8vo.,  paper  50 

RECONSTRUCTION:  INDUSTRIAL,  FINANCIAL,  AND  PO- 
LITICAL. Letters  to  the  Hon.  Henry  Wilson,  U.  S.  S.  8vo 
paper  ......  .  50 

THE  PUBLIC   DEBT,   LOCAL  AND    NATIONAL.      How  to 

provide  for  its  discharge  while  lessening  the  burden  of  Taxa- 
tion. Letter  to  David  A.  Wells,  Esq.,  U.  S.  Revenue  Commis- 
sion. 8vo.,  paper  .  .  .  .  •  «  .  25 

THE  RESOURCES  OF  THE  UNION.  A  Lecture  read,  Dec. 
1865,  before  the  American  Geographical  and  Statistical  So- 
ciety, N.  Y.,  and  before  the  American  Association  for  the  Ad- 
vancement of  Social  Science,  Boston  ...  60 

THE  SLAVE  TRADE,  DOMESTIC  AND  FOREIGN;  Why  it 
Exists,  and  How  it  may  be  Extinguished.  12mo.,  cloth  $1  5<? 


HENRY  CAREY  BAIRD'S  CATALOGUE. 


THE    WAY    TO    OUTDO    ENGLAND    WITHOUT    FIGHTING 
HER.     Letters  to  the  Hon.  Schuyler  Colfax.    8vo.,  paper  $1  00 


.—  A  TREATISE  ON  THE  TEETH  OF  WHEELS: 

Demonstrating  the  best  forms  which  can  be  given  to  them  for  the 
purposes  of  Machinery,  such  as  Mill-work  and  Clo^k-work.  Trans- 
lated from  the  French  of  M.  CAMUS.  By  JCIIK  I.  HAWKINS. 
Illustrated  by  40  plates.  8vo  ......  $300 

PLOUGH.—  THE  CONTRACTOR'S  MANUAL  AND  BUILDER'S 
U    PRICE-BOOK  : 

Designed  to  elucidate  the  method  of  ascertaining,  correctly, 
the  value  and  Quantity  of  every  description  of  Work  and  Ma- 
terials used  in  the  Art  of  Building,  from  their  Prime  Cost  in 
any  part  of  the  United  States,  collected  from  extensive  expe- 
rience and  observation  in  Building  and  Designing;  to  which 
are  added  a  large  variety  of  Tables,  Memoranda,  etc.,  indis- 
pensable to  all  engaged  or  concerned  in  erecting  buildings  of 
any  kind.     By  A.  B.  CLOUGH,  Architect,  24mo.,  cloth  75 

pOLBURN,—  THE  GAS-WORKS  OF  LONDON: 

Comprising  a  sketch  of  the  Gas-works  of  the  city,  Process  of 
Manufacture,  Quantity  Produced,  Cost,  Profit,  etc.    By  ZERAH 
COLBURN.     8vo.,  cloth       ......  75 

nOLBURN.—  THE  LOCOMOTIVE  ENGINE  : 

Including  a  Description  of  its  Structure,  Rules  for  Estimat- 
ing its  Capabilities,  and  Practical  Observations  on  its  Construc- 
tion and  Management.     By  ZERAH  COLBURN.     Illustrated.    A 
new  edition.     12mo.          .         .         .         ...         .     $1  25 

riOLBURN  AND  MAW.—  THE  WATER-WORKS  OF  LONDON: 
Together  with  a  Series  of  Articles  on  various  other  Water- 
works.    By  ZERAH  COLBURN  and  W.  MAW.     Reprinted  from 
"  Engineering."     In  one  volume,  8vo.        .  .     $4  00 

TV1GUERREOTYPIST  AND  PHOTOGRAPHER'S  COMPANION: 
**     12mo.,  cloth     .....     •    .         .         .     $1  25 

TjUPLAIS,—  A  COMPLETE  TREATISE  ON  THE  DISTILLATION 
U    AND    PREPARATION  OF  ALCOHOLIC  AND  OTHER  LIQ- 
UORS: 

From  the  French  of  M.  DUPLAIS.     Translated  and  Edited  by  M. 
M.  D,    Illustrated.     8vo.     (In  press.) 


10  HENRY  CAREY  BATRD'S  CATALOGUE. 

TJIRCKS.— PERPETUAL  MOTION : 

Or  Search  for  Self-Motive  Power  during  the  17tb,  18th,  and 
19th  centuries.  Illustrated  from  various  authentic  sources  in 
Papers,  Essays,  Letters,  Paragraphs,  and  numerous  Patent 
Specifications,  with  an  Introductory  Essay  by  HENRY  DIRCKS, 
C.  E.  Illustrated  by  numerous  engravings  of  machines. 
12mo.,  cloth $3  50 

•niXON.— THE  PRACTICAL  MILLWRIGHT'S  AND  ENGINEER'S 
**     GUIDE : 

Or  Tables  for  Finding  the  Diameter  and  Power  of  Cogwheels  ; 
Diameter,  Weight,  and  Power  of  Shafts ;  Diameter  and  Strength 
of  Bolts,  etc.  etc.  By  THOMAS  DIXON.  12mo.,  cloth.  $1  50 

TpNC AN.— PRACTICAL  SURVEYOR'S  GUIDE: 

Containing  the  necessary  information  to  make  any  person,  of 
common  capacity,  a  finished  land  surveyor  without  the  aid  of 
a  teacher.  By  ANDREW  DUNCAN.  Illustrated.  12mo.,  cloth. 

$1  25 

TjUSSAUCE.— A  NEW  AND    COMPLETE    TREATISE    ON  THE 
^     ARTS  OF  TANNING,  CURRYING,  AND  LEATHER  DRESS- 
ING: 

Comprising  all  the  Discoveries  and  Improvements  made  in 
France,  Great  Britain,  and  the  United  States.  Edited  from 
Notes  and  Documents  of  Messrs.  Sallerou,  Grouvelle,  Duval, 
Dessables,  Labarraque,  Payen,  Rene*,  De  Fontenelle,  Mala- 
peyre,  etc.  etc.  By  Prof.  H.  DUSSAUCE,  Chemist.  Illustrated 

by  212  wood  engravings.     8vo $10  00 

TpSSAUCE.— A  GENERAL  TREATISE  ON  THE  MANUFACTURE 
•  OF  SOAP,  THEORETICAL  AND  PRACTICAL: 
Comprising  the  Chemistry  of  the  Art,  a  Description  of  all  the  Raw 
Materials  and  their  Uses.  Directions  for  the  Establishment  of  a 
Soap  Factory,  with  the  necessary  Apparatus,  Instructions  in  the 
Manufacture  of  every  variety  of  Soap,  the  Assay  and  Determination 
of  the  Value  of  Alkalies,  Fatty  Substances,  Soaps,  etc.  etc.  By 
PROFESSOR  H.  DUSSAUCE.  With  an  Appendix,  containing  Ex- 
tracts from  the  Reports  of  the  International  Jury  on  Soaps,  as 
exhibited  in  the  Paris  Universal  Exposition,  1867,  numerous 
Tables,  etc.  etc.  Illustrated  by  engravings.  In  one  volume  8vo. 
of  over  800  pages $10  00 


IIENHY  CAREY  BAIRD'S  CATALOGUE.  II 

TpSSAUCE.— A  PRACTICAL  GUIDE  FOB  THE  PERFUMER: 

Being  a  New  Treatise  on  Perfumery  the  most  favorable  to  the 
Beauty  without  being  injurious  to  the  Health,  comprising  a 
Description  of  the  substances  used  in  Perfumery,  the  Form- 
ulae of  more  than  one  thousand  Preparations,  such  as  Cosme- 
tics, Perfumed  Oils,  Tooth  Powders,  Waters,  Extracts,  Tinc- 
tures, Infusions,  Vinaigres,  Essential  Oils,  Pastels,  Creams, 
Soaps,  and  many  new  Hygienic  Products  not  hitherto  described. 
Edited  from  Notes  and  Documents  of  Messrs.  Debay,  Lunel, 
etc.  With  additions  by  Professor  H.  Bus  SAUCE,  Chemist.  12mo. 

$3  00 

TjTTSSAUCE.— PRACTICAL  TREATISE  ON  THE  FABRICATION 
"     OF  MATCHES,   GUN  COTTON,  AND  FULMINATING  POW- 
DERS. 

By  Professor  H.  DUSSAUCE.     12mo.  .         .         .     $3  00 

TlUSSAUCE.— A  GENERAL  TREATISE  ON  THE  MANUFACTURE 
"    OF  VINEGAR,  THEORETICAL  AND  PRACTICAL. 

•Comprising  the  various  methods,  by  the  slow  and  the  quick  pro- 
cesses, with  Alcohol,  Wine,  Grain,  Cider,  and  Molasses,  as  wen 
as  the  Fabrication  of  Wood  Vinegar,  etc.  By  Prof.  H,  DUSSAUCE. 
I2mo.  (In  press.) 

TJE  GRAFF.— THE  GEOMETRICAL  STAIR-BUILDERS'  GUIDE : 

Being  a  Plain  Practical  System  of  Hand-Railing,  embracing  all 
its  necessary  Details,  and  Geometrically  Illustrated  by  22  Steel 
Engravings  ;  together  with  the  use  of  the  most  approved  princi- 
ples of  Practical  Geometry.  By  SIMON  DK  GRAFF,  Architect. 
4to $5  00 

TJYER  AND  COLOR-MAKER'S  COMPANION  : 

Containing  upwards  of  two  hundred  Receipts  for  making  Co- 
lors, on  the  most  approved  principles,  for  all  the  various  styles 
and  fabrics  now  in  existence ;  with  the  Scouring  Process,  and 
plain  Directions  for  Preparing,  Washing-off,  and  Finishing  the 
Goods.  In  one  vol.  12mo $1  25 

•DASTON.—  A  PRACTICAL  TREATISE  ON  STREET  OR  HORSE- 

•"     POWER  RAILWAYS : 

Their  Location,  Construction,  and  Management ;  with  General 
Plans  and  Rules  for  their  Organization  and  Operation ;  toge- 
ther with  Examinations  as  to  their  Comparative  Advantages 
over  the  Omnibus  System,  and  Inquiries  as  to  their  Value  for 
Investment ;  including  Copies  of  Municipal  Ordinances  relat- 
ing thereto.  By  ALEXANDER  EASTON,  C.  E.  Illustrated  by  23 
plates,  8vo.,  cloth  .  .  .  .  .  ,  .  $2  00 


12  HENRY  CAREY  BAIRD'S  CATALOGUE. 

pJBSYTH.— BOOK  OF  DESIGNS  FOB  HEAD-STONES,  MUBAL, 
L      AND  OTHER  MONUMENTS  : 

Containing  78  Elaborate  and  Exquisite  Designs.     By   FORSYTE . 

4to.     (In  press) 

pAIBBAIBN.— THE  PBINCIPLES  OF  MECHANISM  AND  MA- 
X      CHINEBY  OF  TBANSMISSION  : 

Comprising  the  Principles  of  Mechanism,  Wheels,  and  Pulleys, 
Strength  and  Proportions  of  Shafts,  Couplings  of  Shafts,  and 
Engaging  and  Disengaging  Gear.  By  WILLIAM  FAIRBAIRN, 
Esq.,  C.  E.,  LL.  D.,  F.  R.  S.,  F.  G.  S.,  Corresponding  Member 
of  the  National  Institute  of  France,  and  of  the  Royal  Academy 
of  Turin ;  Chevalier  of  the  Legion  of  Honor,  etc.  etc.  Beau- 
tifully illustrated  by  over  150  wood-cuts.  In  one  volume  12mo. 

$2  60 
pAIBBAIBN.— PBIME-MOVEBS : 

Comprising  the  Accumulation  of  Water-power ;  the  Construc- 
tion of  Water-wheels  and  Turbines ;  the  Properties  of  Steam ; 
the  Varieties  of  Steam-engines  and  Boilers  and  Wind-mills. 
By  WILLIAM  FAIRBAIRN,  C.  E.,  LL.  D.,  F.  R.  S.,  F.  G.  S.  Au- 
thor of  "Principles  of  Mechanism  and  the  Machinery  of  Trans- 
mission." With  Numerous  Illustrations.  In  one  volume.  (In 
press.) 

T7LAMM.— A  PBACTICAL  GUIDE  TO  THE  CONSTBUCTION  OF 
£      ECONOMICAL  HEATING  APPLICATIONS  FOB  SOLID  AND 
GASEOUS  FUELS: 

With  the  Application  of  Concentrated  Heat,  and  on  Waste 
Heat,  for  the  Use  of  Engineers,  Architects,  Stove  and  Furnace 
Makers,  Manufacturers  of  Fire  Brick,  Zinc,  Porcelain,  Glass, 
Earthenware,  Steel,  Chemical  Products,  Sugar  Refiners,  Me- 
tallurgists, and  all  others  employing  Heat.  By  M.  PIERRE 
FLAMM,  Manufacturer.  Illustrated.  Translated  from  the 
French.  One  volume,  12mo.  (In  press.) 

QILBABT.— A  PBACTICAL  TBEATISE  ON  BANKING: 
^    By  JAMES  WILLIAM  GILBART.     To  which  is  added:  THE  NA- 
TIONAL BANK  ACT  AS  NOW  is  FORCE.     8vo.        .        .     $4  50 

PESNEB.— A  PBACTICAL  TBEATISE  ON  COAL,  PETBOLEUM, 
U   AND  OTHEB  DISTILLED  OILS. 

By  ABRAHAM  GESNER,  M.  D.,  F.  G.  S.  Second  edition,  revised 
and  enlarged.  By  GEORGE  WELTDEN  GESNER,  Consulting 
Chemist  and  Engineer.  Illustrated.  8vo.  .  .  $3  50 


HEXHY  CAREY  BAIRD'S  CATALOGUE.  13 

QOTHIC  ALBUM  FOE  CABINET  MAKERS : 

Comprising  a  Collection  of  Designs  for  Gothic  Furniture.  Il- 
lustrated by  twenty-three  large  and  beautifully  engraved 
plates.  Oblong $3  00 

p  RANT.— BEET-ROOT    SUGAR    AND  CULTIVATION  OF  THE 
U     BEET : 

By  E.  B.  GRANT.     12mo $1  25 

QSEGORY.— MATHEMATICS  FOR  PRACTICAL  MEN  : 

Adapted  to  the  Pursuits  of  Surveyors,  Architects,  Mechanics, 
and  Civil  Engineers.  By  OLINTHUS  GREGORY.  8vo.,  plates, 
cloth $3  00 

gRISWOLD.— RAILROAD  ENGINEER'S  POCKET  COMPANION. 

Comprising  Rules  for  Calculating  Deflection  Distances  and 
Angles,  Tangential  Distances  and  Angles,  and  all  Necessary 
Tables  for  Engineers ;  also  the  art  of  Levelling  from  Prelimi- 
nary Survey  to  the  Construction  of  Railroads,  intended  Ex- 
pressly for  the  Young  Engineer,  together  with  Numerous  Valu- 
able Rules  and  Examples.  By  W.  GRISWOLD.  12mo.,  tucks. 

$1  75 
nUETTIER.— METALLIC  ALLOYS : 

Being  a  Practical  Guide  to  their  Chemical  and  Physical  Pro- 
perties, their  Preparation,  Composition,  and  Uses.  Translated 
from  the  French  of  A.  GUETTIER,  Engineer  and  Director  of 
Founderies,  author  of  "  La  Fouderie  en  France,"  etc.  etc.  By 
A.  A.  FESQUET,  Chemist  and  Engineer.  In  one  volume,  12mo. 
(In  press,  shortly  to  be  published.) 

TTATS  AND  FELTING: 

A  Practical  Treatise  on  their  Manufacture.  By  a  Practical 
Hatter.  Illustrated  by  Drawings  of  Machinery,  &c.,  8vo. 

TTAY.— THE  INTERIOR  DECORATOR: 

The  Laws  of  Harmonious  Coloring  adapted  to  Interior  Decora- 
tions :  with  a  Practical  Treatise  on  House-Painting.  By  D. 
R.  HAY,  House-Painter  and  Decorator.  Illustrated  by  a  Dia- 
gram of  the  Primary,  Secondary,  and  Tertiary  Colors.  12mo. 

$2  25 

TTUGHES.— AMERICAN    MILLER    AND    MILLWRIGHT'S    AS- 

11     SISTABT : 

By  WM.  CARTER  HUGHES.  A  n&w  edition.  In  one  volume, 
12mo.  .  •  .  .  $1  60 


t4  HENRY  CAREY  BAIRD'S  CATALOGUE. 


TJUNT 


—  THE  PRACTICE  OF  PHOTOGRAPHY. 

By  ROBERT  HUNT,  Vice-President  of  the  Photographic  Society, 
London,  with  numerous  illustrations.  12mo.,  cloth  .  75 

TTURST.—  A  HAND-BOOK  FOR  ARCHITECTURAL  SURVEYORS  : 

Comprising  Formulae  useful  in  Designing  Builder's  work,  Table 
of  Weights,  of  the  materials  used  in  Building,  Memoranda 
connected  with  Builders'  work,  Mensuration,  the  Practice  of 
Builders'  Measurement,  Contracts  of  Labor,  Valuation  of  Pro- 
perty, Summary  of  the  Practice  in  Dilapidation,  etc.  etc.  By 
J.  F.  HURST,  C.  E.  2d  edition,  pocket-book  form,  full  bound 

$2  50 
JER  VIS.  —RAILWAY  PROPERTY  : 

A  Treatise  on  the  Construction  and  Management  of  Railways  ; 
designed  to  afford  useful  knowledge,  in  the  popular  style,  to  the 
holders  of  this  class  of  property  ;  as  well  as  Railway  Mana- 
gers, Officers,  and  Agents.  By  JOHN  B.  JERVIS,  late  Chief 
Engineer  of  the  Hudson  River  Railroad,  Croton  Aqueduct,  &c. 
One  vol.  12mo.,  cloth  ......  $2  00 

JOHNSON.—  A  REPORT  TO  THE  NAVY  DEPARTMENT  OF  THE 
U      UNITED  STATES  ON  AMERICAN  COALS  : 

Applicable  to  Steam  Navigation  and  to  other  purposes.     By 

WALTER  R.  JOHNSON.     With  numerous  illustrations.     607  pp. 

8vo.,  half  morocco     ....... 

JOHNSON.—  THE  COAL  TRADE  OF  BRITISH  AMERICA  : 

With  Researches  on  the  Characters  and  Practical  Values  of 

American  and  Foreign  Coals.     By  WALTER  R.  JOHNSON,  Civil 

and  Mining  Engineer  and  Chemist.     8vo.  . 

JOHNSTON.—  INSTRUCTIONS  FOR  THE  ANALYSIS   OF  SOILS, 
U      LIMESTONES,  AND  MANURES. 

By  J.  W.  F.  JOHNSTON.     12mo  .....  3J 

T7-EENE.—  A  HAND-BOOK  OF  PRACTICAL  GAUGING, 

For  the  Use  of  Beginners,  to  which  is  added  A  Chapter  on  Dis- 
tillation, describing  the  process  in  operation  at  the  Custom 
House  for  ascertaining  the  strength  of  wines.  By  JAMES  B. 
KEENE,  of  H.  M.  Customs.  8vo  .....  $1  25 

J7-ENTISH  —  A  TREATISE  ON  A  BOX  OF  INSTRUMENTS, 

•^    And  the  Slide  Rule  ;  with  the  Theory  of  Trigonometry  and  Lo- 

garithms, including  Practical  Geometry,  Surveying,  Measur- 

ing of  Timber,  Cask  aud  Malt  Gauging,  Heights,  and  Distances. 

By  THOMAS  KENTISH.     In  one  volume.     12mo.  .     $1  25 


HEXRY  CAREY  BAIRD'S  CATALOGUE.  15 

J£OBELL.— ERNL— MINERALOGY  SIMPLIFIED  : 

A  short  method  of  Determining  and  Classifying  Minerals,  by 
means  of  simple  Chemical  Experiments  in  the  Wet  Way. 
Translated  from  the  last  German  Edition  of  F.  VON  KOBELL, 
with  an  Introduction  to  Blowpipe  Analysis  and  other  addi- 
tions. By  HENRI  ERNI,  M.  D.,  Chief  Chemist,  Department  of 
Agriculture,  author  of  "  Coal  Oil  and  Petroleum."  In  one 
volume,  12mo.  .  .  .  .  .  .  .  $2  60 

TAFFINEUR.— A  PEACTICAL  GUIDE  TO  HYDRAULICS  FOB 
*-*     TOWN  AND  COUNTRY; 

Or  a  Complete  Treatise  on  the  Building  of  Conduits  for  Water 
for  Cities,  Towns,  Farms,  Country  Residences,  Workshops,  etc. 
Comprising  the  means  necessary  for  obtaining  at  all  times 
abundant  supplies  of  Drinkable  Water.  Translated  from 
the  French  of  M.  JULES  LAFFINEUR,  C.  E.  Illustrated.  (In 
press.) 

TANDRIN.— A  TREATISE  ON  STEEL : 

Comprising  its  Theory,  Metallurgy,  Properties,  Practical  Work, 
ing,  and  Use.  By  M.  H.  C.  LANDRIN,  Jr.,  Civil  Engineer. 
Translated  from  the  French,  with  Notes,  by  A.  A.  FESQUET,  Che- 
mist and  Engineer.  With  an  Appendix  on  the  Bessemer  and  the 
Martin  Processes  for  Manufacturing  Steel,  from  the  Report  of 
Abram  S.  Hewitt,  United  States  Commissioner  to  the  Universal 
Exposition,  Paris,  1867.  12mo $3  00 

T  ARKIN.— THE  PRACTICAL  BRASS  AND  IRON  FOUNDER'S 
*-*     GUIDE : 

A  Concise  Treatise  on  Brass  Founding,  Moulding,  the  Metals 
and  their  Alloys,  etc. ;  to  which  are  added  Recent  Improve- 
ments in  the  Manufacture  of  Iron,  Steel  by  the  Bessemer  Pro- 
cess, etc.  etc.  By  JAMES  LARKIN,  late  Conductor  of  the  Brass 
Foundry  Department  in  Reany,  Neafie  &  Co.'s  Penn  Works, 
Philadelphia.  Fifth  edition,  revised,  with  Extensive  addi- 
tions. In  one  volume,  12mo $2  25 


16        HENRY  CAREY  BAIRD'S  CATALOGUE. 

T  EAVITT—  FACTS  ABOUT  PEAT  AS  AN  ARTICLE  OF  FUEL : 
With  Remarks  upon  its  Origin  and  Composition,  the  Localities 
in  which  it  is  found,  the  Methods  of  Preparation  and  Manu- 
facture, and  the  various  Uses  to  which  it  is  applicable ;  toge- 
ther with  many  other  matters  of  Practical  and  Scientific  Inte- 
rest. To  which  is  added  a  chapter  on  the  Utilization  of  Coal 
Dust  with  Peat  for  the  Production  of  an  Excellent  Fuel  at 
Moderate  Cost,  especially  adapted  for  Steam  Service.  By  H. 
T.  LEAVITT.  Third  edition.  12mo.  .  .  .  $1  75 

TEROUX  —  A    PEACTICAL    TREATISE    ON    THE    MANUFAC- 

^     TUBE  OF  WORSTEDS  AND  CARDED  YARNS: 

Translated  from  the  French  of  CHARLES  LEROUX,  Mechanicaf 
Engineer,  and  Superintendent  of  a  Spinning  Mill.  By  Dr  H. 
PAINE,  and  A.  A.  FESQUET.  Illustrated  by  12  large  plates,  In 
one  volume  8vo $5  00 

TESLIE  (MISS).— COMPLETE  COOKERY: 

Directions  for  Cookery  in  its  Various  Branches.  By  Miss 
LESLIE.  60th  edition.  Thoroughly  revised,  with  the  addi- 
tion of  New  Receipts.  In  1  vol.  12mo.,  cloth  .  .  $1  50 

T  ESLIE  (MISS).  LADIES'  HOUSE  BOOK  : 

a  Manual  of  Domestic  Economy.  20th  revised  edition.  12mo., 
cloth  .  ....  .  .  .  .  .  $1  25 

TESLIE    (MISS).— TWO    HUNDRED    RECEIPTS    IN    FRENCH 
*-*     COOKERY. 

12mo 50 

TIEBER.— ASSAYER'S  GUIDE : 

Or,  Practical  Directions  to  Assayers,  Miners,  and  Smelters,  for 
the  Tests  and  Assays,  by  Heat  and  by  Wet  Processes,  for  the 
Ores  of  all  the  principal  Metals,  of  Gold  and  Silver  Coins  and 
Alloys,  and  of  Coal,  etc.  By  OSCAR  M.  LIBBER.  12mo.,  cloth 

$1  25 

T  OVE.— THE  ART  OF  DYEING,  CLEANING,  SCOURING,  AND 

*~*     FINISHING : 

On  the  most  approved  English  and  French  methods;  being 
Practical  Instructions  in  Dyeing  Silks,  Woollens,  and  Cottons, 
Feathers,  Chips,  Straw,  etc.;  Scouring  and  Cleaning  Bed  and 
Window  Curtains,  Carpets,  Rugs,  etc.;  French  and  English 
Cleaning,  etc.  By  THOMAS  LOVE.  Second  American  Edition,  to 
which  are  added  General  Instructions  for  the  Use  of  Aniline 
G'olors.  8vo.  .  .  5  00 


HENRY  CAREY  BAIRD'S  CATALOGUE.  17 

TV/TAIN  AND  BROWN.— QUESTIONS  ON  SUBJECTS  CONNECTED 
1V1  WITH  THE  MARINE  STEAM-ENGINE : 

And  Examination  Papers ;  with  Hints  for  their  Solution.  By 
THOMAS  J.  MAIN,  Professor  of  Mathematics,  Royal  Naval  College, 
and  THOMAS  BROWN,  Chief  Engineer,  R.  N.  12mo.,  cloth  $1  50 

TWTAIN  AND  BROWN.— THE  INDICATOR  AND  DYNAMOMETER: 

With  their  Practical  Applications  to  the  Steam-Engine.  By 
THOMAS  J.  MAO,  M.  A.  F.  R.,  Ass't  Prof.  Royal  Naval  College, 
Portsmouth,  and  THOMAS  BROWN,  Assoc.  Inst.  C.  E.,  Chief  En- 
gineer, R.  N.,  attached  to  the  R.  N.  College.  Illustrated.  From 
the  Fourth  London  Edition.  8vo.  ...  .  $1  50 

TWTAIN  AND  BROWN.— THE  MARINE  STEAM-ENGINE. 

•"•^  By  THOMAS  J.  MAIN,  F.  R.  Ass't  S.  Mathematical  Professor  at 
Royal  Naval  College,  and  THOMAS  BROWN,  Assoc.  Inst.  C.  E. 
Chief  Engineer,  R.  N.  Attached  to  the  Royal  Naval  College. 
Authors  of  "Questions  Connected  with  the  Marine  Steam-En- 
gine," and  the  li  Indicator  and  Dynamometer."  With  numerous 
Illustrations.  In  one  volume  8vo.  .  .  .  .  .  $5  00 

TUT ARTIN.— SCREW-CUTTING  TABLES,  FOR  THE  USE  OF  ME- 

1V1  CHANICAL  ENGINEERS: 

Showing  the  Proper  Arrangement  of  Wheels  for  Cutting  the 
Threads  of  Screws  of  any  required  Pitch ;  with  a  Table  for 
Making  the  Universal  Gas-Pipe  Thread  and  Taps.  By  W.  A. 
MARTIN,  Engineer.  8vo 50 

TUTILES— A  PLAIN  TREATISE  ON  HORSE-SHOEING. 

With  Illustrations.  By  WILLIAM  MILES,  author  of  "  The  Horse's 
Foot"  . $1  00 

lypLESWORTH.— POCKET-BOOK  OF  USEFUL  FORMULAE  AND 

1V1  MEMORANDA  FOR  CIVIL  AND  MECHANICAL  EN3INEERS. 
By  GUILFORD  L.  MOLESWORTH,  Member  of  the  Institution  of 
Civil  Engineers,  Chief  Resident  Engineer  of  the  Ceylon  Railway. 
Second  American  from  the  Tenth  London  Edition.  In  one 
volume,  full  bound  in  pocket-book  form  .  .  .  .  $2  00 

TyrOORE.— THE  INVENTOR'S  GUIDE : 

Patent  Office  and  Patent  Laws  :  or,  a  Guide  to  Inventors,  and  a 
Book  of  Reference  for  Judges,  Lawyers,  Magistrates,  and  others. 

By  J   G.  MOORE.     12mo.,  cloth $1  25 

RAPIER.— A  MANUAL  OF  ELECTRO-METALLURGY : 

Including  the  Application  of  the  Art  to  Manufacturing  Processes. 
By  JAMES  NAPIER.  Fourth  American,  from  the  Fourth  London 
edition,  revised  and  enlarged.  Illustrated  by  engravings.  In 
one  volume,  8vo $2  00 


18  HENRY  CAREY  BAIRD'S  CATALOGUE. 


TyjAPIER.— A  SYSTEM  OF  CHEMISTRY  APPLIED  TO  DYEING  : 
•^  By  JAMES  NAPIER,  F.  C.  S.  A  New  a^d  Thoroughly  Revised 
Edition,  completely  brought  up  to  the  present  state  of  the 
Science,  including  the  Chemistry  of  Coal  Tar  Colors.  By  A.  A. 
FESQUET, -Chemist  and  Engineer.  With  an  Appendix  on  Dyeing 
and  Calico  Printing,  as  shown  at  the  Paris  Universal  Exposition 
of  1867,  .from  the  Reports  of  the  International  Jury,  etc.  Illus- 
trated. In  one  volume  8vo.,  400  pages  .  .  .  $5  00 

•VTEWBERY.  — GLEANINGS    FROM    ORNAMENTAL    ART    OF 
•"    EVERY  STYLE; 

Drawn  from  Examples  in  the  British,  South  Kensington,  Indian, 
Crystal  Palace,  and  other  Museums,  the  Exhibitions  of  1851  and 
1862,  and  the  best  English  and  Foreign  works.  In  a  series  of  one 
hundred  exquisitely  drawn  Plates,  containing  many  hundred  ex- 
amples. By  ROBERT  NEWBERY.  4to.  ....  $15  00 

JJICHOLSON.— A  MANUAL  OF  THE  ART  OF  BOOK-BINDING: 

Containing  full  instructions  in  the  different  Branches  of  Forward- 
ing, Gilding,  and  Finishing.  Also,  the  Art  of  Marbling  Book- 
edges  and  Paper.  By  JAMES  B.  NICHOLSON.  Illustrated.  12mo. 
cloth  ....  $2  25 

Tfl-ORRIS.— A  HAND-BOOK  FOR  LOCOMOTIVE  ENGINEERS  AND 

1N    MACHINISTS: 

Comprising  the  Proportions  and  Calculations  for  Constructing 
Locomotives ;  Manner  of  Setting  Valves ;  Tables  of  Squares, 
Cubes,  Areas,  etc.  etc.  By  SEPTIMUS  NORRIS,  Civil  and  Me- 
chanical Engineer.  New  edition.  Illustrated,  12mo.,  cloth 

$2  00 

•VTYSTROM.  —  ON    TECHNOLOGICAL    EDUCATION    AND   THE 
1)1    CONSTRUCTION  OF  SHIPS  AND  SCREW  PROPELLERS : 

For  Naval  and  Marine  Engineers.  By  JOHN  W.  NYSTROM,  late 
Acting  Chief  Engineer  U.  S.  N.  Second  edition,  revised  with 
additional  matter.  Illustrated  by  seven  engravings.  12mo. 

$2  50 

NEILL.— A  DICTIONARY  OF  DYEING  AND  CALICO  PRINT- 
ING: 

Containing  a  brief  account  of  all  the  Substances  and  Processes  in 
use  in  the  Art  of  Dyeing  and  Printing  Textile  Fabrics  :  with  Prac- 
tical Receipts  and  Scientific  Information.  By  CHARLES  O'NEILL, 
Analytical  Chemist ;  Fellow  of  the  Chemical  Society  of  London  ; 
Member  of  the  Literary  and  Philosophical  Society  of  Manchester  ; 
Author  of  "  Chemistry  of  Calico  Printing  and  Dyeing."  To  which 
is  added  An  Essay  on  Coal  Tar  Colors  and  their  Application  to 


0 


HENRY  CAREY  BAIRD'S  CATALOGUE.  19 

Dyeing  and  Calico  Printing.  By  A.  A.  FESQUET,  Chemist  and 
Engineer.  With  an  Appendix  on  Dyeing  and  Calico  Printing,  as 
shown  at  the  Exposition  of  1867,  from  the  Reports  of  the  Interna. 
tional  Jury,  etc.  In  one  volume  8vo.,  491  pages  .  .  $6  00 

QSBORN.— THE  METALLURGY  OF  IRON  AND  STEEL : 

Theoretical  and  Practical":  In  all  its  Branches  ;  With  Special  Re- 
ference to  American  Materials  and  Processes.  By  II.  S.  OSBORN, 
LL.  D.,  Professor  of  Mining  and  Metallurgy  in  Lafayette  College, 
Easton,  Pa.  Illustrated  by  230  Engravings  on  Wood,  and  6 
Folding  Plates.  8vo.,  972  pages $10  00 

QSBORN.— AMERICAN  MINES  AND  MINING  : 

^     Theoretically  and  Practically  Considered.     By  Prof.  H.  S.    OS- 
BORN,  Illustrated  by  numerous  engravings.  8vo.   (In  preparation.) 

pAINTER,  GILDER,  AND  VARNISHER'S  COMPANION : 

Containing  Rules  and  Regulations  in  everything  relating  to  the 
Arts  of  Painting,  Gilding,  Varnishing,  and  Glass  Staining,  with 
numerous  useful  and  valuable  Receipts ;  Tests  for  the  Detection 
of  Adulterations  in  Oils  and  Colors,  and  a  statement  of  the  Dis- 
eases and  Accidents  to  which  Painters,  Gilders,  and  Varnishers 
are  particularly  liable,  with  the  simplest  methods  of  Prevention 
and  Remedy.  With  Directions  for  Graining,  Marbling,  Sign  Writ- 
ing, and  Gilding  on  Glass.  To  which  are  added  COMPLETE  INSTRUC- 
TIONS FOR  COACH  PAINTING  AND  VARNISHING.  12mo.,  cloth,  $1  50 

pALLETT.— THE    MILLER'S,    MILLWRIGHT'S,    AND    ENGI- 

*     NEER'S  GUIDE. 

By  HENRY  PALLETT.     Illustrated.     In  one  vol.  12mo.      .     $3  00 

pERKINS.— GAS  AND  VENTILATION. 

Practical  Treatise  on  Gas  and  Ventilation.  With  Special  Relation 
to  Illuminating,  Heating,  and  Cooking  by  Gas.  Including  Scien- 
tific Helps  to  Engineer-students  and  others.  With  illustrated 
Diagrams.  By  E.  E.  PERKINS.  12mo.,  cloth  .  .  .  $1  25 

pERZINS  AND  STOWE.— A  NEW  GUIDE  TO  THE  SHEET-IRON 

L     AND  BOILER  PLATE  ROLLER: 

Containing  a  Series  of  Tables  showing  the  Weight  of  Slabs  and 
Piles  to  Produce  Boiler  Plates,  and  of  the  Weight  of  Piles  and  the 
Biases  of  Bars  to  Produce  Sheet-iron ;  the  Thickness  of  the  Bar 
Gauge  in  Decimals  ;  the  Weight  per  foot,  and  the  Thickness  on 
the  Bar  or  Wire  Gauge  of  the  fractional  parts  of  an  inch ;  the 
Weight  per  sheet,  and  the  Thickness  on  the  Wire  Gauge  of  Sheet- 
iron  of  various  dimensions  to  weigh  112  Ibs.  per  bundle  ;  and  the 
conversion  of  Short  Weight  into  Long  Weight,  and  Long  Weight 
into  Short.  Estimated  and  collected  by  G.  H.  PERKINS  and  J.  G- 
STOWE  .  $2  50 


20  HENRY  CAREY  BAIRD'S  CATALOGUE. 


pHILLI 

•L  TUrC"T 


PS  AND  DARLINGTON.— RECORDS  OF  MINING  AND 
METALLURGY : 

Or,  Facts  and  Memoranda  for  the  use  of  the  Mine  Agent  and 
Smelter.  By  J.  ARTHUR  PHILLIPS,  Mining  Engineer,  Graduate  of 
the  Imperial  School  of  Mines,  France,  etc.,  and  JOHN  DARLINGTON. 
Illustrated  by  numerous  engravings.  In  one  vol.  12mo.  .  $2  00 

pRADAL,    MALEPEYRE,     AND    DUSSAUCE.  —  A    COMPLETE 

*     TREATISE  ON  PERFUMERY: 

Containing  notices  of  the  Raw  Material  used  in  the  Ait,  and  the 
Best  Formulae.  According  to  the  most  approved  Methods  followed 
in  France,  England,  and  the  United  States.  By  M.  P.  PRADAL, 
Perfumer-Chemist,  and  M.  F.  MALEPEYRE.  Translated  from  the 
French,  with  extensive  additions,  by  Prof.  H.  DUSSAUCE.  8vo.  $10 

pROTEAUX.— PRACTICAL   GUIDE  FOR  THE  MANUFACTURE 

I  OF  PAPER  AND  BOARDS. 

By  A.  PROTEAUX,  Civil  Engineer,  and  Graduate  of  the  School  of 
Arts  and  Manufactures,  Director  of  Thiers's  Paper  Mill,  'Puy-de- 
Dome.  With  additions,  by  L.  S.  LE  NORMAND.  Translated  from 
.the  French,  with  Notes,  by  HORATIO  PAINE,  A.  B.,  M.  D.  To 
which  is  added  a  Chapter  on  the  Manufacture  of  Paper  from  Wood 
in  the  United  States,  by  HENRY  T.  BROWN,  of  the  "American 
Artisan."  Illustrated  by  six  plates,  containing  Drawings  of  Raw 
Materials,  Machinery,  Plans  of  Paper-Mills,  etc.  etc.  8vo.  $5  00 

•REGNAULT.— ELEMENTS  OF  CHEMISTRY. 

By  M.  V.  REGNAULT.  Translated  from  the  French  by  T.  FOR- 
EEST  BENTON,  M.  B.,  and  edited,  with  notes,  by  JAMES  C.  BOOTH, 
Melter  and  Refiner  U.  S.  Mint,  and  WM.  L.  FABER,  Metallurgist 
and  Mining  Engineer.  Illustrated  by  nearly  700  wood  engravings. 
Comprising  nearly  1500  pages.  In  two  vols.  8vo.,  cloth  $10  00 

T)EID.— A  PRACTICAL  TREATISE  ON  THE  MANUFACTURE  OF 

*"    PORTLAND  CEMENT: 

By  HENRY  REID,  C.  E.  To  which  is  added  a  Translation  of  M. 
A.  Lipowitz's  Work,  describing  anew  method  adopted  in  Germany 
of  Manufacturing  that  Cement.  By  W.  F.  REID.  Illustrated  by 
plates  and  wood  engravings.  8vo $7  00 

•pIFFAULT,    VERGNAUD,    AND    TOUSSAINT.— A   PRACTICAL 

II  TREATISE    ON   THE    MANUFACTURE    OF    COLORS    FOR 
PAINTING: 

Containing  the  best  Formulae  and  the  Processes  the  Newest  and 
in  most  General  Use.  By  MM.  RIFFAULT,  VERGNAUD,  and  TOUS- 
SAINT. Revised  and  Edited  by  M.  F.  MALEPEYRE  and  Dr.  EMIL 
WINCKLER.  Illustrated  by  Engravings.  In  one  vol.  8vo.  (In 
Reparation.) 


HENRY  CAREY  BAIRD'S  CATALOGUE.  21 

TDIFFAULT,   VERGNAUD,    AND    TOUSSAINT.—A    PRACTICAL 
11    TREATISE  ON  THE  MANUFACTURE  OF  VARNISHES : 

By  MM.  RIFFAULT,  VERGNAUD,  and  TOUSSAINT.  Revised  and 
Edited  by  M.  F.  MALEPEYRE  and  Dr.  EMIL  WINCKLER.  Illus- 
trated. In  one  vol.  8vo.  (In  preparation.) 

CHUNK.— A  PRACTICAL  TREATISE    ON   RAILWAY   CURVES 
°    AND  LOCATION,  FOR  YOUNG  ENGINEERS. 

By  WM.  F.  SHUNK,  Civil  Engineer.    12mo.,  tucks    .         .     $2  00 

OMEATON.— BUILDER'S  POCKET  COMPANION: 

Containing  the  Elements  of  Building,  Surveying,  and  Architec. 
ture  ;  with  Practical  Rules  and  Instructions  connected  with  the  sub- 
ject. By  A.  C.  SMEATON,  Civil  Engineer,  etc.  In  one  volume, 
12mo $i  50 

HMITH.— THE  DYER'S  INSTRUCTOR: 

Comprising  Practical  Instructions  in  the  Art  of  Dyeing  Silk,  Cot- 
ton, AVool,  and  AYorsted,  and  Woollen  Goods  :  containing  nearly 
800  Receipts.  To  which  is  added  a  Treatise  on  the  Art  of  Pad- 
ding; and  the  Printing  of  Silk  Warps,  Skeins,  and  Handkerchiefs, 
and  the  various  Mordants  and  Colors  for  the  different  styles  of 
such  work.  By  DAVID  SMITH,  Pattern  Dyer,  12mo.,  cloth 

$3  00 

qMITH.— THE  PRACTICAL  DYER'S  GUIDE: 

^  Comprising  Practical  Instructions  in  the  Dyeing  of  Shot  Cobourgs, 
Silk  Striped  Orleans,  Colored  Orleans  from  Black  Warps,  ditto 
from  White  Warps,  Colored  Cobourgs  from  White  Warps,  Merinos, 
Yarns,  AVoollen  Cloths,  etc.  Containing  nearly  300  Receipts,  to 
most  of  which  a  Dyed  Pattern  is  annexed.  Also,  a  Treatise  on 
the  Art  of  Padding.  By  DAVID  SMITH.  In  one  vol.  8vo.  $25  00 

.—CIVIL  ARCHITECTURE: 

Being  a  Complete  Theoretical  and  Practical  System  of  Building, 
containing  the  Fundamental  Principles  of  the  Art.  By  EDWARD 
SHAW,  Architect.  To  which  is  added  a  Treatise  on  Gothic  Archi- 
tecture, Ac.  By  THOMAS  W.  SILLOWAY  and  GEORGE  M.  HARD- 
ING ,  Architects.  The  whole  illustrated  by  102  quarto  plates  finely 
engraved  on  copper.  Eleventh  Edition.  4to.  Cloth.  $10  00 


glOAN 


.—AMERICAN  HOUSES: 

A  variety  of  Original  Designs  for  Rural  Buildings.  Illustrated  by 
26  colored  Engravings,  with  Descriptive  References.  By  SAMUEL 
SLOAN,  Architect,  author  of  the  "Model  Architect,"  etc.  etc.  8vo. 

$2  50 


22  HENRY  CAREY  BAIRD'S  CATALOGUE. 

gMITH.— PARKS  AND  PLEASURE  GROUNDS  : 

Or,  Practical  Notes  on  Country  Residences,  Villas,  Public  Parks, 
and  Gardens.  By  CHARLES  H.  J.  SMITH,  Landscape  Gardener 
and  Garden  Architect,  etc.  etc.  12mo $2  25 

qTOKES.— CABINET-MAZER'S  AND  UPHOLSTERER'S  COMPA- 

0  NION : 

.  Comprising  the  Rudiments  and  Principles  of  Cabinet-making  and 
Upholstery,  with  Familiar  Instructions,  Illustrated  by  Examples 
for  attaining  a  Proficiency  in  the  Art  of  Drawing,  as  applicable 
to  Cabinet-work  ;  The  Processes  of  Veneering,  Inlaying,  and 
Buhl-work  ;  the  Art  of  Dyeing  and  Staining  Wood,  Bone,  Tortoise 
Shell,  etc.  Directions  for  Lackering,  Japanning,  and  Varnishing; 
to  make  French  Polish ;  to  prepare  the  Best  Glues,  Cements,  and 
Compositions,  and  a  number  of  Receipts,  particularly  for  workmen 
generally.  By  J.  STOKES.  In  one  vol.  12mo.  With  illustrations 

$1  25 

STRENGTH  AND  OTHER  PROPERTIES  OF  METALS. 

Reports  of  Experiments  on  the  Strength  and  other  Properties  of 
Metals  for  Cannon.  With  a  Description  of  the  Machines  for  Test- 
ing Metals,  and  of  the  Classification  of  Cannon  in  service.  By 
Officers  of  the  Ordnance  Department  U.  S.  Army.  By  authority 
of  the  Secretary  of  War.  Illustrated  by  25  large  steel  plates.  In 
1  vol.  quarto .  $10  00 

rjiABLES  SHOWING  THE  WEIGHT  OF  ROUND,  SQUARE,  AND 

1  FLAT  BAR  IRON,  STEEL,  ETC. 

By  Measurement.     Cloth 63 

rpAYLOR.— STATISTICS  OF  COAL: 

Including  Mineral  Bituminous  Substances  employed  in  Arts  and 
Manufactures  ;  with  their  Geographical,  Geological,  and  Commer- 
cial Distribution  and  amount  of  Production  and  Consumption  on 
the  American  Continent.  With  Incidental  Statistics  of  the  Iron 
Manufacture.  By  R.  C.  TAYLOR.  Second  edition,  revised  by  S. 
S.  HALDEMAN.  Illustrated  by  five  Maps  and  many  wood  engrav- 
ings. 8vo.,  cloth  ....  *'*  ,.  9  .  .  $6  00 

rpEMPLETON.— THE    PRACTICAL   EXAMINATOR    ON    STEAM 
1     AND  THE  STEAM-ENGINE  : 

With  Instructive  References  relative  thereto,  for  the  Use  of  Engi- 
neers, Students,  and  others.  By  WM.  TEMPLETON,  Engineer  ]2mo. 

$1  25 

mHOMAS.— THE  MODERN  PRACTICE  OF  PHOTOGRAPHY. 

•*•     By  R.  W.  THOMAS,  F.  C.  S.     8vo.,  cloth  .         ...  75 


mu 


HENRY  CAREY  BAIRD'S  CATALOGUE.  23 

OMSON.— FREIGHT  CHARGES  CALCULATOR. 

By  ANDREW  THOMSON,  Freight  Agent  .  .  .  .  $1  25 
RNING :  SPECIMENS  OF  FANCY  TURNING  EXECUTED  ON 
THE  HAND  OR  FOOT  LATHE: 

With  Geometric,  Oval,  and  Eccentric  Chucks,  and  Elliptical  Cut- 
ting Frame.  By  an  Amateur.  Illustrated  by  30  exquisite  Pho- 
tographs. 4to $3  00 

rpURNER'S  (THE)  COMPANION: 

Containing  Instructions  in  Concentric,  Elliptic,  and  Eccentric 
Turning;  also  various  Plates  of  Chucks,  Tools,  and  Instru- 
ments; and  Directions  for  using  the  Eccentric  Cutter,  Drill, 
Vertical  Cutter,  and  Circular  Rest ;  with  Patterns  and  Instruc- 
tions for  working  them.  A  new  edition  in  1  vol.  12mo.  $1  50 

TTRBIN  —  BRULL.  —  A   PRACTICAL    GUIDE    FOR   PUDDLING 
U    IRON  AND  STEEL. 

By  ED.  URBIN,  Engineer  of  Arts  and  Manufactures.  A  Prize 
Essay  read  before  the  Association  of  Engineers,  Graduate  of  the 
School  of  Mines,  of  Liege,  Belgium,  at  the  Meeting  of  1865-6. 
To  which  is  added  a  COMPARISON  OF  THE  RESISTING  PROPERTIES 
OF  IRON  AND  STEEL.  By  A.  BRULL.  Translated  from  the  French 
by  A.  A.  FESQUET,  Chemist  and  Engineer.  In  one  volume,  8vo. 

$1  00 

ARN.— THE  SHEET  METAL  WORKER'S  INSTRUCTOR,  FOR 
ZINC,  SHEET-IRON,  COPPER  AND  TIN  PLATE  WORK- 
ERS, &c. 

By  REUBEN  HENRY  WARN,  Practical  Tin  Plate  Worker.  Illus- 
trated by  32  plates  and  37  wood  engravings.  8vo.  .  .  $3  CO 

ATSON.— A  MANUAL  OF  THE  HAND-LATHE. 

By  EGBERT  P.  WATSON,  Late  of  the  "  Scientific  American,"  Au- 
thor of  ' '  Modern  Practice  of  American  Machinists  and  Engi- 
neers," In  one  volume,  12mo.  .  .  .  .  $1  50 

ATSON.— THE  MODERN  PRACTICE  OF  AMERICAN  MA- 
CHINISTS AND  ENGINEERS: 

Including  the  Construction,  Application,  and  Use  of  Drills,  Lathe 
Tools,  Cutters  for  Boring  Cylinders,  and  Hollow  Work  Generally, 
with  the  most  Economical  Speed  of  tke  same,  the  Results  verified 
by  Actual  Practice  at  the  Lathe,  the  Vice,  and  on  the  Floor. 
Together  with  Workshop  management,  Economy  of  Manufacture, 
the  Steam-Engine,  Boilers,  Gears,  Belting,  etc.  etc.  By  EGBERT 
P.  WATSON,  late  of  the  "Scientific  American."  Illustrated  by 
eighty-six  engravings.  12mo. $2  50 


W 


W 


W 


24  HENRY  CAREY  BAIRD'S  CATALOGUE. 

TTTATSON.— THE  THEORY  AND  PRACTICE   OF  THE  ART  OF 
V  WEAVING  BY  HAND  AND  POWER: 

With  Calculations  and  Tables  for  the  use  of  those  connected  with 
the  Trade.  By  JOHN  WATSON,  Manufacturer  and  Practical  Machine 
Maker.  Illustrated  by  large  drawings  of  the  best  Power-Looms. 
8vo $10  00 

TTP-EATHERLY.— TREATISE    ON  .THE  ART   OF  BOILING   SU- 
VV  GAR,    CRYSTALLIZING,     LOZENGE-MAKING,     COMFITS, 
GUM  GOODS, 

And  other  processes  for  Confectionery,  &c.     In  which  are  ex- 
plained, in  an  easy  and  familiar  manner,  the  various"  Methods 
.     of  Manufacturing  every  description  of  Raw  and  Refined  Sugar 
Goods,  as  sold  by  Confectioners  and  others        .         .  $2  00 

.—TABLES  FOR  QUALITATIVE  CHEMICAL  ANALYSIS. 

By  Prof.  HEINRICH  WILL,  of  Giessen,  Germany.  Seventh  edi- 
tion. Translated  by  CHARLES  F.  HIMES,  Ph.  D.,  Professor  of 
Natural  Science,  Dickinson  College,  Carlisle,  Pa.  .  .  $1  25 

WILLIAMS.— ON  HEAT  AND  STEAM : 

Embracing  New  Views  of  Vaporization,  Condensation,  and  Expan- 
sion. By  CHARLES  WYE  WILLIAMS,  A.  I.C.  E.  Illustrated.  8vo. 

$3  50 

•VTTTOHLER.— A  PRACTICAL  TREATISE  ON  ANALYTICAL  CHE- 

VV  MISTRY. 

By  F.  Wohler.  With  additions  by  GRANDEAU  and  TROOST. 
Edited  by  H.  B.  NASON,  Professor  of  Chemistry,  Rensselaer  In- 
stitute, Troy,  N.  Y.  With  numerous  Illustrations.  (In  press.) 

RSSAM.— ON  MECHANICAL  SAWS : 

From  the  Transactions  of  the  Society  of  Engineers,  1867.  By 
S.  W.  WORSSAM,  Jr.  Illustrated  by  18  large  folding  plates.  8vo. 

$5  00 

A  RLOT.— A  COMPLETE  GUIDE  FOR  COACH  PAINTERS. 

Translated  from  the  French  of  M.  ARLOT,  Coach  Painter ;  late 
Master  Painter  for  eleven  years  with  M.  Ehrler,  Coach  Manufac- 
turer, Paris.  With  important  American  additions.  (In  press.) 


yOGDES.— THE  ARCHITECT'S  AND  BUILDER'S  POCKET  COM- 
V    PANION. 

By  F.  W.  VOGDES,  Architect.    Illustrated.    Full  bound  in  pocket- 
book  form.      (In  press.) 


THIS  BOOK  IS  DUE  ON  THE  LAST  DATE 
STAMPED  BELOW 


AN     INITIAL     FINE     OF    25     CENTS 

WILL  BE  ASSESSED  FOR  FAILURE  TO  RETURN 
THIS  BOOK  ON  THE  DATE  DUE.  THE  PENALTY 
WILL  INCREASE  TO  5O  CENTS  ON  THE  FOURTH 
DAY  AND  TO  $1.OO  ON  THE  SEVENTH  DAY 
OVERDUE. 


APR  0 


JAN    2  1936 


REC'D  LD 

JANl5'64-lPM 


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UNIVERSITY  OF  CALIFORNIA  LIBRARY 


